-mregparm=3 (was Re: [PATCH] i386 do_machine_check() is redundant.
From: Mikulas Patocka (mikulas_at_artax.karlin.mff.cuni.cz)
Date: 09/29/03
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Date: Mon, 29 Sep 2003 22:20:45 +0200 (CEST) To: Arjan van de Ven <arjanv@redhat.com>
> > > Use machine_check_vector in the entry code instead.
> >
> > This is wrong. You just lost the "asmlinkage" thing, which means that it
> > breaks when asmlinkage matters.
> >
> > And yes, asmlinkage _can_ matter, even on x86. It disasbles regparm, for
> > one thing, so it makes a huge difference if the kernel is compiled with
> > -mregparm=3 (which used to work, and which I'd love to do, but gcc has
> > often been a tad fragile).
>
> gcc 3.2 and later are supposed to be ok (eg during 3.2 development a
> long standing bug with regparm was fixed and now is believed to work)...
> since our makefiles check gcc version already... this can be made gcc
> version dependent as well for sure..
They are still buggy. gcc 3.3.1 miscompiles itself with -mregparm=3
(without -O or -O2 it works). (I am too lazy to spend several days trying
to find exactly which function in gcc was miscompiled, maybe I do it one
day). gcc 2.95.3 compiles gcc 3.3.1 with -mregparm=3 -O2 correctly.
gcc 3.4 doesn't seem to be better.
gcc 2.7.2.3 has totally broken -mregparm=3, even quite simple programs
fail.
Mikulas
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- Previous message: bill davidsen: "Re: [PROBLEM] [2.6.0-test6] Stale NFS file handle"
- In reply to: Arjan van de Ven: "Re: [PATCH] i386 do_machine_check() is redundant."
- Next in thread: Daniel Jacobowitz: "Re: -mregparm=3 (was Re: [PATCH] i386 do_machine_check() is redundant."
- Reply: Daniel Jacobowitz: "Re: -mregparm=3 (was Re: [PATCH] i386 do_machine_check() is redundant."
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