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Subject: Linux Frequently Asked Questions 3/4 [monthly posted]
Summary: Linux, a small and free unix for 386-AT computers.
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Date: 24 Nov 92 23:22:11 GMT
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Archive-name: linux-faq/part3
Last-Modified: 92/11/20
Version: 1.11

*********************************************************
*                            *
*   Answers to Frequently asked questions about Linux   *
*                            *
*********************************************************

This post contains Part 3 of the Linux FAQ (4 parts).
It must be read *after* the 2 first parts.

===================================8<====>8============================
CONTENTS (of this part)

    VIII.    FEATURES            (part3)
    IX.    GCC MISC INFORMATION        (part3)
    X.    SCSI SPECIAL            (part3)

===================================8<====>8============================



VIII. FEATURES
==============

QUESTION: I've read that linux has virtual consoles, what must I do to
get them?

ANSWER: Yes there are, you can access them with the left <alt>-key
together with <Fn>-key. With the Linux Images distribution, 4 consoles
are available, getty runs on them.
Notice that they are NOT accessible when running X (contrary to some
commercial unices).

QUESTION: When Linux boots, I get the following message "8 virtual
consoles"; how can I acess to the 5-8 vc's ?

ANSWER: If you want the getty to run on the 5-8, you should add the
corresponding entries in /etc/inittab. You can also just run sh on
them by using the doshell soft.
And then in either case, the ALT-F[5-8] will access the corresponding
vc.

QUESTION: What kind of shell is /bin/sh ?

ANSWER: It's the Bourne Again Shell, bash-1.12.3 and
compilation was straightforward, just "make"
that's all or nearly.
BTW There does exist different shells for Linux, these are:
bash, rc, zsh, tcsh and pdksh (a korn shell).


QUESTION: Does there exist a man page for **** ?

ANSWER: Download man.tar.Z from your favorite linux ftp site, there is
most of the fileutils man page -- either **** or g****, example there
is nothing on ld, but there is for gld :) --, check the whatis
database provided. The files in the cat1 dir are pre-formatted man
pages that the man program can use. Quite recently the man pages for
section 2 have been written (thanks Drew) and can be found, at least
at tsx-11 in /pub/linux/docs/man/man2.tar.Z

Also manpages are in the SLS on the b? disks.

BTW there is nroff and groff for Linux. Cawf 2.0 works just
fine for simple man pages, and a partial ms support too.


Moreover Michael Johnson is the coordinator for man pages under Linux,
he is looking for volunteers, so contact the DOC Channel.

QUESTION: Is there a simple man package (groff is too big):

ANSWER: "Cawf -man" also "fm -m" (Al Clark) tsx-11 in
     /pub/linux/binaries/usr.bin/fm.tar.Z


QUESTION: What are the editors available in linux?

ANSWER: Right now there are uemacs-3.11, elvis-1.4 (1.5).
Gnu Emacs is there, read the section devoted to it in the 4th part of
this FAQ. Also the port of mg (micro gnu) has been done and can be
found at least at athos.rutgers.edu (128.6.4.4)
in pub/linux, mg is the binary and mg.tar.Z is the sources file. You
can also find a PD ed, and elvis has an ex mode. Finnally there are
joe, vile-3.11, elle (Elle Looks Like Emacs), Xedit and aXe.

QUESTION: Does there exist a printer package for Linux?

ANSWER: (R. Miller) Yes.  The "plp" package is currently available
under the directory [/pub/linux]/BETA/plp on tsx-11 and its mirrors.
You may also print things manually like so:  cat filename > /dev/lp1
(Note that though "/dev/lp0" exists, most people find that their
printer is on /dev/lp1.  Use whatever the kernel says that it detects
in the boot-up messages.)


QUESTION: How do I make swapping work?

ANSWER: Quite simply, you need the swapon and the mkswap binaries.
Then you can choose between a swap partition or a swap file.
The mkswap is used to write the "swap signature", whilst the swapon
binary is to activate the swapping.

First of all you need a partition :), I assume it's the second of your
first disk namely /dev/hda2, and it's 10MB big
A) swap partition:
you have to indicate it's a swap area, this is done via mkswap
(instead of mkfs) which needs the name of the partition and the size
in blocks (a block is 1Ko big); the optional -c flag is for bad block
checking. So for our example you should perform:
mkswap [-c] /dev/hda2 10000
Then you need to indicate that you want linux to use the swap area,
this is done via swapon. In general it is set in the /etc/rc file,
just put the following entry:
/bin/swapon /dev/hda2
It can also be achieved via the /etc/fstab file
B) swap file:
The process is quite close; you need a partition, and a swap file.
Assume that I prefer a swap area of 4MB (I want to keep some place in
/dev/hda2). I need first to "dd" the file.
dd if=/dev/hda2 of=/swap_file bs=1024 count=4096
bs stands for block size, and count is the number of blocks
then I have to put the "swap signature" on that file:
mkswap /swap_file 4096
At this point, you should 'sync', just to be sure the signature is
effective. And finally add an entry in the rc file:
/bin/swapon /swap_file


QUESTION: When I boot I get one of the following messages:
"Unable to find swap signature" or "Bad swap-space bitmap"

ANSWER: You probably forgot to make your swap-device, use the mkswap
command.


QUESTION: How do I know if it is swapping?

ANSWER: You will notice it :)) First of all, Linux tells you at boot
time, "Adding swap: XXX pages of swap space", and if you start running
out of memory, you will notice that the disk will work overtime, and
things slow down. Generally a 2Meg RAM will make the system swap
constantly while running gcc, 4 Meg will swap occasionnaly when
optimizing big files (and having other things active, such as make).
Also, the command 'free' (from the ps package) reports total enabled
swap space and current swap use.


QUESTION: How is it possible to remove a swap file?

ANSWER: Simply perform a rm on that file, and remove the swapon of
your /etc/rc file.


QUESTION: How is it possible to remove a swap device?

ANSWER: mkfs the device, and remove the swapon of your /etc/rc file.

QUESTION: How much swap space do I need ?

ANSWER: Linux does not perform real swapping, it's rather paging (see
below for a more complete explanation). The swap area is *added* to
the memory and can be viewed as virtual memory, so choose the size you
need, example:

        8MB RAM + 6MB swap => 14MB virtual memory

QUESTION: Could someone explain the swap process on Linux?, is it
swapping or paging ?

ANSWER: (Linus) Linux uses swap as /additional/ memory, one page of
the swap-space is used for the good-page bitmap and the swapspace
signature.
In fact Linux does only paging, no swaping in the meaning "write out
one whole process to disk".
The reason it's called swapping is that Linux used paging for memory
management on a low level since the very beginning, but didn't page to
disk at all until 0.12.

QUESTION: Is demand paging different from paging and How ?

ANSWER: (Linus) Demand-paging is really "demand loading of
executables" and is totally independent of the page-swapping
algorithms, although they have similarities. When Linux strts up a
process, no actual code space is loaded: I let the page exceptions
load in the executable as needed. Thus Linux demand-loads the code and
initialized data it needs.
Demand-loading has very good points: (a) it simplifies the exec system
call; (b) it means page sharing between that have excuted the same
file is easy to implement; (c) it cuts down on the amount of memory
required. When Linux runs out of real memory, it starts to lock for
pages it can swap out, but if it notices that the page is clean, it
just forgets about it, and demand-loads it when it's needed again.
Thta means that swap-file isn't needed as much, especially when
running big binaries such as gcc, where the code-pages can be
demand-loaded as you wish.

Point (c) means that even without any swap space, you can usually run
slightly larger programs that your memory setup would actually permit.
I've noticed this while running X and doing a kernel compilation +
something else wshen I've forgotten to turn on swapping: free reports
0 page available but things still work, although performance is
slightly down...

QUESTION: Is there any way to tell how much swap space you are using
or have left?

ANSWER: The free program provided with the ps package handles this.


QUESTION: I have a 2Megs box, but "free" reports only 1Meg why?

ANSWER: (Linus:) "free" doesn't concern with the memory the kernel has
allocated for itself. In other words what you see is the *user* memory
available. The kernel has taken the low 1Meg for it's use (~250Ko for
it and the rest for buffer cache and kernel data structures); for big
memory machine it could be even 2Megs.

QUESTION: What tape drives work with Linux ?

ANSWER: (24 sept. P. Riipinen)
- There is a working QIC-02 device driver for Linux, supporting (at
  least) Everex/Wangtek cards.
- There are additional patches for the QIC-02 to support Archive
  SC402/499R. You can find them in /pub/linux/alpha/qic-02 at tsx-11
  There are some bugs in the driver but you can backup.
- Newer drivers are all SCSI, so check the SCSI section in this FAQ.

QUESTION: Is there only the %$#@ keyboard ?

ANSWER: There are Dannish, Finnish, French, German, Uk, US and DVORAK
keyboards. Set it in the main Makefile of the kernel sources, then
(re)compile the kernel again. Make sure the files in kernel/chr_drv
directory are recompiled.


QUESTION: (special FINNISH/US) I booteed up with the new image and
everything work except that some keyboard keys produce wrong
characters. Does anyone know what is happening?

ANSWER: Since 0.95a images are US product (and so are US-keyboard
oriented), BUT linux sources are FINNISH product, and so the default
keyboard is set to be FINNISH. The solution is in the previous Q/A.


QUESTION: Does there exist shared libs ?

ANSWER: (H.J. Lu, [e-mail], 09/01/92)

The shared library under Linux started at 0.12. Peter MacDonald
collaborating with Linus made the first generation of shared library,
which is the base of the current classic shared library.

The kernel support of shared library under Linux is system call

extern int uselib (const char *__filename);

which loads an executable image with fixed entry point into memory,
just like the ordinary executables.

In crt0.s, a function which can find out if and which shared images
are needed and loads them is invoked before `main ()' is called if
necessary. David Engel and I developed a way to tell the loader which
shared images have to be loaded, utilizing the similar technique used
in global constructor in g++ 2.x with the help from GNU binary
utilities.

In the classic Linux shared library, we build a big executable image
for several libraries and make sure no external variables outside of
the participating libraries are referenced. Then we can get the
absolute addresses of all the global variables defined in the
libraries used to build that executable image. After that, we make a
stub library for each participating library which just has the
absolute addresses of all the global variable in it.

For each shared image, there must be one and only one file, usually
called, __shared.o, which defines a global variable containing
version, name and entry point of the shared image, and a dummy global
data. Among those libraries used to build the shared image, there must
be one library which will always be referenced whenever any other
library is referenced. We put `__shared.o' into the stub library for
that library and add a declaration for the dummy global data defined
in `__shared.o' which will make sure `__shared.o' will always be linked
in when any participating libraries are linked.

In gcc 2.2.2d, jump table, developed by David Engel, was introduced in
the shared library. At the beginning of each shared image, there is
a table in which every library function has a fixed entry address and
the instruction at that address is a jump which will lead to the
real library function. So we can change the library function without
changing the corresponding entry address of the jump table. For the
global data we put them at the beginning of data section of the shared
image. We have to separate them from text code and link them in fixed
order. It is very hard to maintain the same addresses for the global
data when library is changed. After the global data are set up properly
and some spaces are left for possible future changes (that is a very
tough procedure.), it isn't too difficult to maintain.

In the current implementation, only libc.a, libcurses.a, libdbm.a,
libtermcap.a and libm.a are built with jump table. The global data in
X11 libraries are too complicated to make jump table such that their
addresses won't change when there is a change in X11 libraries. It's
not apparent yet that the benefits gained from a jump table version of
the X libraries would offset the effort required to set it up and
maintain it unless we get some cooperation from X Consortium, which
is very unlikely. But they are linked with jump table version of
libc.a and libm.a. That means they don't have to be relinked when
there is a modification in libc.a or libm.a.


QUESTION: Does Linux work for SCSI drives?

ANSWER: Yes since v0.96. At headrest.colorado.edu in /pub/scsi, you
will find the last SCSI alpha/beta version and also a special SCSI
FAQ, read it, it  contains the latter information than the one provided
in the SCSI section. You should, also, contact the linux-scsi list or
directly [e-mail]


QUESTION: Linux is supposed to work with ESDI drive. However I have
trouble with my Magtron MT-4115E (Joincom controler), any clue?

ANSWER: (Linus) Some harddisk don't like linux (even though they
should). Maybe not a bug but a deficiency.
(Mika) I had to remove the printk "unexpected hd interrupt" statement
in hd.c because I was getting so many of those messages. Be warned
that if there is any read error the system just hangs, even the
ctrl-alt-del won't work. You should be able to use your ESDI drives if
you could live with those nuisances.

QUESTION: How does one go about applying a patch to Linux ?

ANSWER: (Drew Eckhardt) In the unix world most of distribution are in
source form. This includes the operating system. To apply a patch, you
apply it with the 'patch' program to the affected sources. The patch
program takes as input the differences between the old and the new
version. After patching you need to recompile the sources.

Assume I want to apply a patch enclosed in the file XXX. First of all
I will look at the top of XXX, where the file affected is identified.
This may have aleading path attached to it. Either cd out to the
"root" of the patch, ie if I see
linux/kernel/blk_drv/blk.h

I would cd into /usr/src
(assuming it's the place where I can find linux/kernel...)
and then patch as follows
patch -p0 < whatever_place/XXX

or, you can specify a number of path components to strip from the
path. If I am in the blk_drv directory patching would be
patch -p3 < whatever_place/XXX


QUESTION: There are a lot of patches available (ps patch, NFS patches,
CD-ROM patches ...) can I be fairly confident the subsequent patches will
work?

ANSWER: This is not true yet for the current version; but it will be
so I kept it :)
No you can't, patching is a real beta tester art :)).  People are not
working on the same patched release, so you have to check if the
patches you already applied works on the same kernel part, if not,
/great/, just apply them. If yes, check if there is an order, patch
creator knows that, and (should) try to warn patch user (in other
words: beta tester) otherwise you should edit the patch files (and
possibly make a brief note to others on this list/newsgroup or even a
cdiff) before applying them, another solution is to keep cool and wait
for the next version of Linux where, in general, the modifications
have been done but this behavior is /not/ Linux helpful.


QUESTION: I got the patches on some ftp sites, and applied them to the
kernel and tried to compile. It didn't !!. Are the patches buggy?

ANSWER: Before remake, just do a make clean in the directories
involved by the patches. This will force a rebuild of the .o and .a
files.
If you have a RCS running on your source tree, did you checked a
patched version of the files changed before /any/ CO either by you or
make

Finally, make sure the patches succeded. Normally, failed patches on a
file FILE will leave a FILE# file. Moreover you will get a "chunk
failed" message. It is possible to capture the output while patching,
with the following:

    patch -p0 < patchfile | 2>&1 patch.result | more


QUESTION: What is VFS?

ANSWER: (Ted) Linux 0.96 already has Virtual FileSystem, which means
that it acts as a filesystem switch. It makes it easy for someone to
design another filesystem format and include it in the Linux kernel
along with the standard minix filesystem format. So it /enables/
someone to design a robust filesystem which would have some nice
properties (no 14 chars file name limitation, nor 64Meg limit), and
could be included in the kernel in such a way that both the Minix and
the new one could be mounted at the same time. This solves the
uncompability problem; since the root disk could still use the Minix
filesystem, while the hardisk could be using the new one.



QUESTION: What's about Bus Mice ?

ANSWER: (Nathan I. Laredo) Since the Linux v0.96c-pl2 the kernel does
support LOGITECH and BUS MICE
If you are unsure that you have a bus mouse or not, check to see if
your mouse card has a selection for a sample rate switchable between
30Hz and 60Hz (or possibly 25/50Hz), if it does not, then it is NOT a
true  bus mouse (InPort mice for example will not work with this
driver).
To create a bus mouse device:
mknod /dev/mouse c 10 0


QUESTION: What's about TeX ?

ANSWER: The primary site for Linux TeX is 129.78.66.1, this is
P. Williams' site in Australia. The stuff at tsx-11 was posted by
T. Dunbar  who does support/maintain the dvilj stuff.


QUESTION: What's about LILO ?

ANSWER: (Werner Almesberger)
LILO  -  Generic Boot Loader for Linux ("LInux LOader")

This is an ALPHA test release of a new boot loader. Be sure to have
some means to boot your system from a different media if you install
LILO on your hard disk.

Features
--------

- does not depend on the file system. (Tested with Minix, EXT FS and MS-DOS
  FS.)
- can be used to boot from floppies and from hard disks.
- can replace the master boot record.
- can boot non-Linux systems (MS-DOS, DR DOS, OS/2, ...) and unstripped
  kernels.
- supports up to 16 different boot images that can be selected at boot
  time. Root and swap disk/partition can be set independently for each
  image.
- boot sector, file map and boot images can be all on different disks or
  partitions.


Restrictions and known problems
-------------------------------

- SCSI disks are not fully supported yet. (Still waiting for some kernel
  changes.)
- booting other operating systems doesn't seem to work everywhere. If
  everything but booting a non-Linux OS from LILO works on your system,
  you should boot LILO by BOOTACTV and select the alternate OS with the
  latter as a temporary work-around.
- booting non-Linux systems from the second hard disk ("D:") is not yet
  supported.

Please send all bug reports to [e-mail]


QUESTION: What's about MGR ?

ANSWER: (General Information grabbed from various sources)
There is a MGR channel available , contact the request adress with
help in the body: [e-mail]
The stuff can be found at banjo in pub/Linux/MGR
In brief:

MGR provides:
    - multiple overlapping windows
    - multiple fonts
    - text and graphics in each windows
    - a simple popup menu package
    - a client/server model 'a la' X
    - independance from any peculiar networking technology

MGR consist of a server process and some clients. Each client has his
own window, and can create subwindows. Clients communicate with the
server via a bidirectionnal channel. A C library is provided.

When a new window starts, it is as a terminal emulator running the
shell; for more information you can grab the mgr-man.out from
bellcore.com


QUESTION: I have successfully compiled MGR, but when I try to run the
program I get "can't find mouse" or "already in use", any clue?

ANSWER: try the following "mgr -m /dev/ttys1" if the mouse is on
the serial 1. Another possibility is to link /dev/mouse with
/dev/ttys1 (assuming your mouse is on serial 1). Or if it's a bus
mouse, "mknod /dev/mouse c 10 0" once.

QUESTION: Any tips for MGR?

ANSWER: Well, I have tried it on my 386Sx Ega/Vga; the screen is Ok
but the Logitech mouse I have is not well recognized.

BTW check the major/minor number for pty's; they should be character
device with 4 as major and 128 and bigger as minor:
ptyp0 c 4 128
ptyp1 c 4 129
...
ttyp0 c 4 192
ttyp1 c 4 193

QUESTION: What's about X11 ?

ANSWER: See the section devoted to X11 in this FAQ.


IX. GCC MISC INFORMATION
========================

The official release of GCC for Linux is 2.2.2d, information for the
previous versions (1.37, 1.40) can be found in FAQ of July 92.

I think this section is needed, 'cause a) gcc is the compiler under
Linux, and b) the gcc-2.x is still evolving, and many information change
constantly.
To conclude this short introduction (in fact the conclusion will be
longer than the introduction :), the most recent release of gcc-2.2.2d
can be found at tsx-11 in /pub/linux/GCC, and also at
fgb1.fgb.mw.tu-muenchen.de under /pub/linux/GCC, and one of the
"specialist" is Hongjiu Lu ([e-mail]). There is a special
channel for GCC, feel free to contact the linux-activists list.
The Information provided in this section which envolved GCC2.xx
are extracted from the FAQ GCC, written by Hongjiu, provided
with the current distribution of gcc /READ IT/
Finally whenever you report a bug please give the version of gcc, the
version of your kernel, otherwise NO ONE can help you.


QUESTION: I don't know how to install gcc stuff, is there special
places?

ANSWER: gcc-2.xx is splitted in 3 main files 2.xxdb.tar.Z,
2.xxlib.tar.Z and 2.xxmisc.tar.Z, some utilities (binutils.tar.Z) and
shared libraries are also provided. To install them do the following:

First of all, backup the old compiler. YOU MUST BE SURE THERE IS NO
OTHER C COMPILER INSTALLED ON YOUR SYSTEM. What is meant by compiler
is all the stuff: binaries, header files, libraries and crt0.o. I
assume that whateverplace contains the 2.xxfiles you have downloaded.

cd /usr
tar xvpzf whateverplace/2.xxmisc.tar.Z

read the FAQ, and README in /usr/install/gcc2.


QUESTION: What are the contents of them?

ANSWER: 2.xxdb.tar.Z contains cpp, libg.a and libc_p.a. 2.xxlib.tar.Z
contains cc1 and cc1plus. 2.xxmisc.tar.Z contains gcc 2.xx drivers,
header files, libraries, manual pages and installation instructions.
Another file, XXXXinc.tar.Z, where XXXX is the current version number
of Linux kernel, has all the header files to replace the header files
from kernel. YOU MUST INSTALL IT. Please read README for details.

(gcc.2.2.2d 08/15/92)
1. 2.2.2ddb.tar.Z (libg.a, libc_p.a and jump stable stuffs)
   You just have to install jump/lib*.so.* by hand.
3. 2.2.2dg1.tar.Z (libg.a compiled with -g1 to get a smaller libg.a)
4. 2.2.2dfix4.tar.Z (<time.h>, <limits.h>,  <unistd.h>, libc.a and
   shared/*.a)
5. shlib-2.2.2d.tar.Z (build the stub libs for the shared libs.)
6. libc-2.2.2dfix4.tar.Z. It has the following files:

    ./posix/sysconf.c

You need to delete by hand libinet.a in
    /usr/lib/gcc-lib/i386-linux/2.2.2d



QUESTION: I seem to be unable to compile anything with gcc. Why?

ANSWER: If you have only 2 MB RAM, gcc will die silently without
compiling anything. You must have at least 4 MB to do compilations

BTW Since swapping is possible, I have heard that compilation works
with only 2Meg and a lot disk traffic :) Isn't it great?


QUESTION: gcc complains about not finding crt0.o and the system
include files What am I doing wrong ?

ANSWER: The include files normal place is in /usr/include. lib*.a and
*.o should be in /usr/lib or /usr/local/lib


QUESTION: I tried to port a /new/ version of gnu stuff. But in the
linking phase, gcc complains about the missing libg.a.


ANSWER: Yes this is well known for compiler version earlier than
2.2.2, throw away the flag -g that's all, anyway libg.a is /only/ for
debugging purpose.


QUESTION: How to compile programs which may be debugged with gdb?

ANSWER: There are different ways to handle this problem. If
you have the gcc2.2.2 or later it's simple, use the -g flag. Otherwise
there are different possibilities:
1) As there is no libg.a, you should throw away the -g flag in link
phase, this means that the compilation must be done in two steps
example: instead of "gcc -g monprog.c -o monprog", use the following
"gcc -g -c monprog.c" and then "gcc -o monprog monprog.o"
Alas this method is not that good if you are using Makefile.
2) The other way is to create an empty libg.a as follows (Peter
Macdonald trick):
- create libfake.c containing libgfake() {}
- compile it with: gcc -c libfake.c
- create the libg.a with: ar r libg.a libfake.o
2bis) The more tricky Humberto method:
cd /usr/lib
ranlib libg.a

then gcc -g monprog.c -o monprog will produce a debuggable monprog


QUESTION: When compiling some code, cc1 complains about some insn
code, what's that?

ANSWER: An insn is an internal representation that gcc uses when
compiling. The main part of gcc is to take ordinary c (or c++) code,
and compile it, while ding optimizations in insn part, which is
soft/hard independant. Then another part which is hard/Os dependant
takes the insns and translate it in assembly language. The fix is only
to turn off the optimization flag (-O).


QUESTION: While compiling some stuff, I'm getting the following
error message:
Undefined symbol ___addsf3 referenced from text segment
as well as ___mulsf3 and __cmpsf2.
These symbols are not in the program or in it's header files.

ANSWER: These are math helper functions, and you can usually compile
these programs to use the kernel floating point routines by adding
'-m80387' to the compiler switches. If the program does any wierd
fp math (exp(), sin()) it'll die when you run it though.



QUESTION What's about gcc2.x ?

ANSWER: It has been ported to linux, it is (pretty) stable and works.
The files are 2.xxlib.tar.Z and 2.xxmisc.tar.Z Uncompress and untar
2.xxmisc, read the FAQ enclosed and play with it.  You can find these
files at tsx-11 in binaries/compilers/gcc-2.x. One of the most recent
version is on tsx-11 and fgb1.
The shlib.tar.Z enables you to create shared libraries, read the
README file included
The 096inc.tar.Z contains the header files from the kernel


QUESTION: I can't run g++ due to the lack of "expr"; where can I find
it ?

ANSWER: In the shellutils-1.6.tar.Z (or whatever is the last release)
on prep.ai.mit.edu

QUESTION: I have grabbed the new gcc2.xx, but I can't use it whenever
I compile (even hello world program) I get "parse error before ('s";
any clue ?

ANSWER: Yes, it's caused by bad compress/tar binaries, use the one
provided at tsx-11 in linux/binaries/usr.bin

QUESTION: Is there a bug in how g++ and gcc handle include files?
'cause I can't get them to find files in the g++-include directory.

ANSWER: Did you run "fixfiles"? The file permission in g++-include is
640 and should be 444.


QUESTION: I've seen on my ftp-server that there are different
***fix*.tar.Z files in the GCC directory, do I need them?

ANSWER: If you got a very early copy of gcc 2.2.2, please get
2.2.2fix1.tar.Z and 2.2.2fix2.tar.Z, and libc-linux.fix.tar.Z for the
C lib sources, and new shlib-2.2.2.tar.Z if you want. If you got gcc
2.2.2 after you saw **fix*.tar.Z, you are fine.

QUESTION: Is stdio ANSI compatible?

ANSWER: Yes, please test it.

QUESTION: Is g++ in 2.xx?

ANSWER: Yes.

QUESTION: How do I use gcc?

ANSWER: Read manual page, gcc.ps or gcc.man in /usr/install/gcc2.

QUESTION: What options can I use for gcc?

ANSWER: Read manual page, gcc.ps or gcc.man. Also -static tells gcc
to use the static libraries, -nojump forces gcc to use the classic
shared libraries. The default is the jump table version of shared
libraries. The shared libraries for X are linked with the jump table
version of shared C library.

QUESTION: Where is the source code of the new libc.a?

ANSWER: The same place you find this file. It is called
lib-src-yy.xx.TZ.

QUESTION: Why does g++ complain, even die?

ANSWER: You need "expr", which is in GNU shell utilities 1.6, echo (?)
and sed.

QUESTION: How do I generate code for 486?

ANSWER: Add -m486 to CFLAGS.

QUESTION: I heard malloc (0) wouldn't work with Linux, what should I
do?

ANSWER: include <stdlib.h> and don't define NO_FIX_MALLOC.

QUESTION: Why does gcc say "xxxxx..h not found"?

ANSWER: see QUESTION: What are the contents of them?

QUESTION: I really followed every step in the documentation, but when
I do "make", why does it say "don't how to make xxxxxx"?

ANSWER: The dependency in Makefile is dated, you need to make a new
one. Please get some guide on make and read Makefile. For the kernel
sources, please do

cd src/linux
make dep

QUESTION: How do I compile programs under Linux?

ANSWER: The Linux C library is trying to be ANSI/POSIX compliant. It
is also very compatible with SYSV and BSD. The C library is loaded
with SYSV and BSD functions. There are three exceptions:

1. signal in Linux is POSIX.
2. tty in Linux is POSIX.
3. time functions are POSIX, plus a few BSD and SYSV extensions.
4. setjmp/longjmp functions are POSIX. But you can use -D__FAVOR_BSD
   to make it BSD or use sigsigjmp/siglongjmp.

When you compile a program under Linux, your best bet is include all
the appropriate header files and use -Wall. All the usable functions
and global variables are declared in the corresponding header files.
YOU SHOULD NOT DEFINE ANY functions or global variables OF THE LINUX C
LIBRARY IN YOUR CODE IF YOU WANT TO USE THE SHARED LIBRARIES.

After saying all those, you now should know you can compile a program
with -D_POSIX_SOURCE or -D_GNU_SOURCE (read <features.h> for details).
With a few modifications you can even use -DSYSV, -DUSG or -DBSD. Some
codes need to define -DSTDC_HEADERS for ANSI C compiler like gcc here.

To use malloc () and calloc () safely under Linux, please include

<stdlib.h> and don't define NO_FIX_MALLOC.

BTW, gcc -traditional should work with gcc 2.2.2d or above.

Please also read ChangeLog for the latest enhencement.

Please read the header files for details. Maybe you should get a book
on POSIX. Any suggestion of the book list?

QUESTION: When compiling #$@!, I've got some problems with "SIGBUS"
signal that doesn't exist. Any clue ?

ANSWER: (Louis J. LaBash, Jr.) SIGBUS is a common problem, its not
needed, just comment it all out, something like:

#ifdef SIGBUS
.. normal sigbus code ..
#endif

QUESTION: How can I write codes suitable for building shared library ?

ANSWER: (H.J. Lu, [e-mail], 09/01/92)
There are some guidelines for writing codes suitable for building the
shared library with jump table.

1. Never, ever allow library users to access global data directly.
   Always, always make them go through access functions.  That way,
   you are free to change the internal implementation, but can
   easily provide backward compatibility by simply replacing the
   access functions.

2. If you do have to define some global data for library users to
   access, put them into a separate file. Never mix them with other
   library code. Also make sure the relative locations of the global
   data will not change very often. One solution is leave some spaces
   for them to grow.

X. SCSI SPECIAL
===============
*** This section is written by Drew Eckhardt, mail him for any
*** information, questions related to this section.
*** Last update November 1992.


QUESTION: What SCSI hosts are supported?

ANSWER: The Adaptec 154x, Adaptec 174x Future Domain 16x0,  Seagate ST0x,
Ultrastor 14F, and Western Digital 7000FASST  are supported.  Various Adaptec
clones from Bustek and Future Domain are known to work, in both ISA and EISA
flavors.

The TMC 950, and the discrete 8xx implementations will be supported
in the new Seagate driver when debugging is finished.  If you want to
use an older kernel, add 0x200 to the status and data register addresses.

Not very many BIOS signatures are included for the Future domain boards, so
they may not auto-detect correctly.

QUESTION: Which disks ?

ANSWER: Anything that works with your host adapter electronically, and
is new enough to support a December 1985 draft of SCSI-I.

Sysquest, and other removeable hard disks are supported.

Extended partitions also work, with 11 Extended partitions per disk
allowed in combination with the four real partitions and whole disk
sub device.

Disks up to two terabytes in size will work, since the sd drier
switches to 10 byte reads when necessary.

QUESTION: What about SCSI tapes ?

ANSWER: Tapes are supported in the alpha SCSI drivers.

QUESTION: What about CD ROMS?

ANSWER: Stable support is in the kernel for SCSI CD-ROM drives, and the
ISO-9660 file system is in beta test.  Rockridge extensions are supported.

QUESTION: How do I get SCSI information?

ANSWER: Subscribe to the SCSI channel of the linux-activists mailing list.
mail [e-mail]
And put in the header.
       X-MN-Admin: join SCSI

QUESTION :  I can't make a filesystem on /dev/hd*

ANSWER : /dev/hd* aren't your SCSI disks.  /dev/sd* are.
See below for approproate major / minor numbers if they
do not exist on your root diskette.

QUESTION: How do I partition the disk?

ANSWER: Use pfdisk or the DOS parititioning program of your choice

QUESTION: My partitioning program can't figure out the disk geoemetry

The problem with partitioning SCSI disks and Linux is that Linux talks
directly to the SCSI interface.  Each disk is viewed as the SCSI host
sees it : N blocks, numbered from 0 to N-1, all error free.  There is
no portable way to get disk geometry.

However, DOS doesn't like things like this, it demmands that BIOS
present it with a normal Cylinder / Head / Sector coordinates.  So,
BIOS does, and it comes up with some fabrication that fits what DOS
wants to see.  You don't want to disagree with what BIOS thinks when
you write the partition table.

The newest SCSI code will return the mapped geometry for some host
adapter / disk combinations. Get the latest SCSI code from
tsx-11.mit.edu:/pub/linux/ALPHA/scsi

QUESTION: The stock {f,pf}disk programs don't work.

ANSWER: At least some older versions of these partitioning programs have
/dev/hd* hardcoded into them, and they don't see /dev/sd*.

If you want, YOU can change the /dev/hd* devices to be links to or
other entries for the SCSI devices.

Also, pfdisk should be callable with a device name.

Hopefully, some one will change the partitioning programs to respect
the SCSI devices.

QUESTION: Where is the latest version maintained?

ANSWER: tsx-11.mit.edu:/pub/linux/ALPHA/scsi

Join the list before you grab anything.

[e-mail] (Eric Youngdale) added scatter/gather support
to the SCSI drivers, and changed around the internal structures to get
something that works as "version 2"

QUESTION: What are the major / minor numbers for SCSI drives?

ANSWER: Because of the large number of devices that can be hung off of
a SCSI bus (as many as 56 if you use SCSI fanouts or bridge boards),
and the possibility of 16 partitions on a SCSI disk, we'd run out of
minor numbers if they were statically allocated - so a dynamic
numbering scheme is used.

Block device major 8 is used for SCSI drives, 9 for SCSI tapes, and
11 for CD-ROMs.

Minors are assigned in increments of 16 to SCSI disks as they are
found, scaning from host 0, ID 0 to host n, ID 7, excluding the host
ID.  Most hosts use ID 7 for themselves.

A minor where minor mod 16 = 0 is the whole drive, where minor mod 16
is between 1 and 4, that partition, extended partitions dynamically
assigned from 5 to 15 inclusive.  Note that the gendisk.c module
prints partition tables on initialization - you should be able to see
them there.

Example : I have four SCSI disks, set up as follows
        Seagate ST02, ID=0
        Seagate ST02, ID = 5
        Ultrastor 14, ID = 0
        Adaptec 1542, ID = 0

The first disk on the seagate at ID 0 will become minors 0-15
inclusive, the second at ID5 16-31 inclusive, the disk on the
Ultrastor 32-47, on the Adaptec 48-63.

QUESTION: How do I reduce kernel bloat and eliminate the drivers I
don't want?

ANSWER: Simply #undef CONFIG_DISTRIBUTION in include/linux/config.h,
and define the macros for the SCSI hosts you want enabled.

QUESTION: I get SCSI timeouts.

ANSWER: Make sure your board has interrupts enabled correctly.

QUESTION: The seagate driver doesn't work.

ANSWER: There are several possibilities
1) Is the board jumpered for IRQ5 ?

The factory settings are
for MSLOSS, and have interrupts disabled.  Interrupts are controlled
by the W3 (ST01) or JP3 (ST02) jumper, which should have pins FG
shorted.  See your manual.

2) Cached machines will not have problems IF the Seagate's address
space (typically C8000 - CAFFFF) is not marked "non cacheable."
This applies to the i486 internal cache as well as i386/i486
external caches.

This can be set in the XCMOS of most machines.  If you can't disable
cache for the Seagate's area (16K in size, starting at the base
address), then you must disable the cache entirely, otherwise
it won't work.

3) The new seagate drivers (not yet released) can operate in a mode where
the 0ws ISA bus line is used to synchronize the ISA and SCSI busses.
This makes things fast, since the alpha Seagate driver can dump SCSI data out
fast enough to swamp the bus.  However, this will only work if the 0ws
jumper is enabled.  If this isn't the case, the Seagate driver "should" detect
this as an over/under run condition, but it might not.  Either enable
the 0ws jumper, or #undef FAST in seagate.h.

QUESTION: The Adaptec driver doesn't work.

ANSWER: The Adaptec BIOS does some initialization that affects
the driver.  If the BIOS was disabled, it may fail on your system.

Older versions of the SCSI drivers ran the 174x in 1542 emulation
mode, where some of these cards have a bug that interferes with
reads / writes > 512 bytes.

The new SCSI drivers support the 174x in 'native' mode, so this isn't
a problem.

QUESTION: What about bugs?

ANSWER: It works on MY hardware.  It works on Tommy Thorn's Adaptec
system, Dave Gentzel's Ultrastor, Thomas Wuensche's WD7000, Rick
Faith's Future Domain, and quite a few other systems.

Bugs that are there will mostly be very hardware specific, and nasty
to track down.  SCSI should be basically error free - consequently,
the error code has not been heavily tested, and there are known bugs
in it.

If you have found a bug, please mail it to the mailing list with
specifics of your hardware.  Other people may have the same problem, a
solution, etc.

If you provide a patch, in context diff form, the bug will be fixed
Immediately.  If you can provide me with a procedure that reproduces
the bug on *MY* system, the bug will be fixed "soon."  Your chances
of getting it fixed increase exponentially with the amount of
information provided.  If I can't reproduce it, and your
description gives me no idea as to where in the code to  look,
it won't get fixed by me.

QUESTION: What are the known bugs?

ANSWER :

Many of the drivers cannot abort a command that is in progress - if
something goes haywire, all drives off that controller will hang.

QUESTION: I get a message saying READ CAPACITY FAILED. What does this
mean?

ANSWER: UPGRADE.

QUESTION: Why does the system "hang" when SCSI disk access occurs.

ANSWER: Older Linux distributions (pre .97)  used  earlier versions
of the SCSI drivers, where the drivers were not interrupt driven
(easier debugging, or so we thought).  Since the drivers did not return
from the device driver strategy routine, until the SCSI command
completed, no other tasks were scheduled, and ineteractive performance
was abysmall.

UPGRADE.

QUESTION: Why can't I swap to a SCSI disk?, Why can't I mount a SCSI
disk as root?

ANSWER: This was due do a race condition that has since been fixed.

UPGRADE.

QUESTION: What future developments are planned?

ANSWER: The following changes will/have occurred :

        - have occurred :

        - support for scatter / gather is there.  This
          means that all read (and readaheads) will be
          handled via one command.

        - Significant changes have been made to the
              Seagate driver.  Among other things, it supports the
          0ws line, which means we can dump data fast enough
          to flood the bus.

        - Multiple outstanding commands per LUN are supported.
          This should result in vastly improved performance
          on multi-device systems.

        - SCSI tapes are supported.

        - Support for LUN !=0 is there.

    - Planned
        - SCSI commands are issued as linked commands
          wherever possible, eliminating the arbitration /
          selection / message out phases needed to start
          a command "from scratch".

        - I have the mode page specs, and am looking at
          doing "appropriate things" w.r.t. cache enable,
          buffer control, etc.  It seems that some drives
          power up, and keep the buffer off until told otherwise
          in software.


QUESTION: What drivers does the new code support.

ANSWER: ALL of the existing drivers work fine.  However, only an Adaptec
scatter/gather driver is included in the alpha package.  The seagate
scatter/gather driver is fast but not yet stable and still kernel
panics.

QUESTION: WHEN?

ANSWER: Again, thanks to Eric's code contributions, it's available in
alpha test now.


       ===================8<==========>8================--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#    LaBRI              |                        #
#  351 cours de la Liberation    |  e-mail:  [e-mail]    #
#  33405 Talence Cedex         |                        #
#                   |                        #
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
  There will be some sig, once our local net will be reliable.
        Right now I rather stay anonymous.