cdrtools/READMEs/README.linux

WARNING: Do not use 'mc' to extract the tar file!
All mc versions before 4.0.14 cannot extract symbolic links correctly.

Linux is the most self incompatible OS I know. If you have any problem,
first carefully read this file.

Linux includes the gnu make program by default but it is called 'make' on linux.
You will definitely need the shell script Gmake.linux to use gmake
on a linux system.

Install it as /usr/bin/Gmake with:

cp Gmake.linux /usr/bin/Gmake

Then compile the system by calling:

/usr/bin/Gmake
or ./Gmake.linux

NOTE for all Linux 2.5.x versions and all Linux versions before 2.6.8:

	Linux did ship with defective kernel include files starting
	with 2.5.x. These defective kernel include files did prevent
	compilation. If you have problems compiling software and see
	error messages related to include/scsi/scsi.h & include/scsi/sg.h
	either upgrade to Linux-2.6.8 or newer or remove /usr/src/linux

NOTE for all Linux versions using libc.so.6:

	Libc.so.6 is definitely a big problem in binary compatibility.
	First you should note that Linux is not a OS but only a kernel.

	Creating a OS from kernel, libraries and applications is done
	by various companies that create "Linux distributions". It seems
	that these companies (e.g. SuSE and Red Hat) are fighting wars
	against each other.

	There is no guarantee that a binary that has been compiled
	on one Linux distribution will run correctly on a different
	release of the same vendor or on a distribution from a different 
	vendor. You cannot copy binaries between different Linux
	versions, always compile the sources by yourself.

	We should consider that the name libc.so.6 is burned out for
	these incompatibility reasons. But stop: Don't be too fast.
	The dynamic linker on Linux does not work correctly. It has
	been derived from the SunOS 4.x linker (which worked correctly)
	but  the Linux version does not even warn if it could not
	find a library with the right major version number. Until
	this is fixed it makes no sense to switch to libc.so.7

	See below for more information.


NOTES for S.u.S.E distributions: If the "make" run aborts with strange messages,
then you need to unset an environment variable called PROMPT_COMMAND
It contains illegal values for a make file system.

		I M P O R T A N T

	please carefully read all notes:

Newer Linux kernels (from 2.3.51) moved SVSv shared memory into a filesystem.
If you get messages with error code EINVAL related to shared memory, you 
most likely installed a newer kernel on an old system that does not mount
the new shared memory filesystem.
For information on this filesystem please read README.linux-shm

If you have any problems to access a device on the SCSI bus, check your
/dev/sg devices first. Your system should either only have /dev/sga...
or /dev/sg0... The newer Linux kernel use /dev/sg0... so the actual
SCSI transport code checks for /dev/sg0... first. Many Linux installations
have too few /dev/sg* device nodes. This is because of the funny device 
mapping. It may be possible that one SCSI device eats up 8 /dev/sg* entries.
I recommend to have at least 20 /dev/sg* device nodes.

In any case: first read the man page for hints how to specify the device.
If nothing helps, first run e.g. cdrecord -scanbus. If this does not find
your device, the problem is in your kernel or system installation.
If scanning the bus finds the device, you are using the wrong device name.
If nothing help try to call e.g. strace cdrecord 

Linux ATAPI hints:

Read README.ATAPI to learn how to use ATAPI drives with the SCSI transport
library.

Linux SCSI hints:

If you want to use the user SCSI library on a target that is connected
to a SCSI hostadapter which is not the first, you need to apply a patch
to your Linux kernel code. This patch is located in the file 

Linux.scsi-patch

Please chdir to /usr/src, call
patch  < Linux.scsi-patch
and re-compile and re-install your kernel.

Linux kernels past 2.0.30 will probably already have this patch included.

I recommend to use Linux 2.0.35 or later or Linux 2.1.115 or later.
These versions of Linux will include ATAPI support in a way needed by cdrecord.
Linux 2.1.115 or newer will in addition support the Parallel Port / ATAPI
adapters found in some CD-R or CD-RW drives.

IMPORTANT:

-	Linux driver design oddities ******************************************
	Although cdrecord supports to use dev=/dev/sgc, it is not recommended
	and it is unsupported.

	The /dev/sg* device mapping in Linux is not stable! Using dev=/dev/sgc
	in a shell script may fail after a reboot because the device you want
	to talk to has moved to /dev/sgd. For the proper and OS independent
	dev=<bus>,<tgt>,<lun> syntax read the man page of cdrecord.

-	Linux Kernel bug ******************************************************
	In some architectures (at least on sparc / alpha / ppc) kernels prior
	to 2.0.32 are not usable because the call to mlockall() kills cdrecord.

-	You configured you kernel the wrong way *******************************
	If you get a message like:

		cdrecord: Function not implemented. shmget failed

	You need to look for three possible reasons:

	-	You are using a Linux Kernel 2.3.51 or newer.
		Read README.linux-shm

	-	You removed SVSv IPC from your kernel. You need to enable it again.
		Run a Linux kernel config and recompile with SYSv IPC.

	-	The allowed amount of shared memory in the kernel is
		not sufficient. See next main point for a solution:

-	Linux kernel oddities *************************************************
	You may need to edit /usr/src/linux/include/asm*/shmparam.h to allow at least 
	4 MB of shared memory for your architecture by modifying SHMMAX
	and re-compile/re-install Linux !
	(note that Linux for Intel by default allows 16 MB) 

	Do this by e.g. changing the #define for SHMMAX to:

	#define SHMMAX 0x1000000                /* max shared seg size (bytes) */

	This will allow 16 MB for shared memory.

-	Linux kernel memory management ****************************************
	If you get the message: "Cannot allocate memory. Cannot send SCSI cmd via ioctl"
	Your kernel/include files are inconsistent.

		This seems to be the case with most actual Linux kernels!!!!!!

	Make sure, that the include file /usr/src/linux/include/scsi/sg.h
	reflects the actual kernel. Usually, the files /usr/include/scsi/sg.h
	and /usr/src/linux/include/scsi/sg.h should be identical.

	**** Never change the content of /usr/src/linux/include/scsi/sg.h without
	properly recompiling the kernel. Cdrecord depends on the fact that
	the value of the define SG_BIG_BUFF uses the same value as the actual
	kernel. Use cdrecord -scanbus -debug to get the value of SG_BIG_BUFF
	with cdrecord has been compiled. An output of:

		scsi_getbuf: 32768 bytes

	indicates that cdrecord has been compiled with 32k SG_BIG_BUF

	The Linux 'sg' driver is the worst driver design, I've ever seen.

-	Linux Binary incompatibility *****************************************
	If any of the options that take a equal sign ('=') in the middle does
	not work correctly (e.g. dev= or if=) you are using a binary that
	does not work correctly on your current OS distribution.

	If dev=0,0,0 does not work but -dev=0,0,0 works you found this
	incompatibility. This problem is caused by an incompatibility
	in ctype.h and it seems that there are other compatibility problems
	e.g. with reading /etc/default/cdrecord.

	You cannot copy binaries between different Linux versions,
	always compile the sources by yourself. 

	If a hint from a user is correct then even a RPM binary built for
	RH-6.2 did not work on RH-6.2 because of these binary incompatibilities.


Joerg