Re: ALERT! Stay away from patched gcc's (was Re: 2.0.22 will be the last version)

Robert L Krawitz (
Sat, 28 Sep 1996 18:36:07 -0400 (EDT)

Date: Sat, 28 Sep 1996 16:57:30 +0300 (EET DST)
From: Linus Torvalds <>

> Hmm --- my system (asus sp3g, ncr53c810 on board, amd5x86-P75, 1G
> SCSI-Disk, SCSI-CDROM) is not able to boot 2.0.21 nor 2.0.20.
> Note: 2.0.0 up to 2.0.18 boots without any problem and 2.0.18 is
> really stable. All kernels are optimized for i486 and 53c7,8xx is
> used.

Ok, I asked Werner to send me a disassembly of the affected
function, and he definitely had some bad code produced by his
compiler for the new inline assembly code to handle semaphores.

If you have problems booting 2.0.19+, make _sure_ you have a good
gcc. I personally use stock 2.7.2, and that is known to be ok. The
bad compiler was also based on gcc-2.7.2, but had some patches
applied (at least a "bugfix" for the strength-reduce bug, and it
may be that that "bugfix" has bad side effects, but I have yet to
hear back whether that was the only patch).

FYI, I'm using 2.0.21 compiled with 2.7.2 + the strength reduce bugfix
with no problems on two configurations: Neptune motherboard, 53c810,
Sony CD, SB AWE32, IDE disk also, and Dell P6-200 with Adaptec 2940UW,
SCSI CDROM. I've used both NCR drivers; Drew's works flawlessly; the
BSD one occasionally locks under heavy load (but it was doing this and
worse for a long time). Other than that problem with the BSD driver,
both systems run flawlessly (the P6 has only been around for a few
days). Both kernels are pentium optimized (486 with less stringent

That said, I have seen some odd code produced on occasion for the
Pentium memcpy speedup (which BTW also wins, but only by 10%, on at
least one P6 system). I've assumed that it's because of my lack of
knowledge of the constraint language, and I did eventually settle on a
good choice of constraints.

Robert Krawitz <> 

Member of the League for Programming Freedom -- mail Tall Clubs International -- or 1-800-521-2512