Hi!
Is there way not to let linux use FPU, MMX, SSE and similar fancy
units? I have athlon processor, but would like to turn FPU (and
similar fancy stuff) off...
Pavel
PS: I'm trying to narrow down sigsegv-after-resume problem... Getting
rid of fancy 486+ features would help me.
--
<sig in construction>
On Wed, 21 Nov 2001, Pavel Machek wrote:
> Is there way not to let linux use FPU, MMX, SSE and similar fancy
> units? I have athlon processor, but would like to turn FPU (and
> similar fancy stuff) off...
You may use "no387" to disable FPU and MMX (they are controlled by a
single bit in cr0). No idea about SSE.
--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: [email protected], PGP key available +
On Thu, 22 Nov 2001, Maciej W. Rozycki wrote:
> On Wed, 21 Nov 2001, Pavel Machek wrote:
>
> > Is there way not to let linux use FPU, MMX, SSE and similar fancy
> > units? I have athlon processor, but would like to turn FPU (and
> > similar fancy stuff) off...
>
> You may use "no387" to disable FPU and MMX (they are controlled by a
> single bit in cr0). No idea about SSE.
Running a kernel optimized for 386 should leave out MMX, SSE and similar
fancy instrucion sets IIRC.
Rasmus
--
-- [ Rasmus 'M?ffe' B?g Hansen ] ---------------------------------------
DISCLAIMER: Microsoft, Windows, Windows 98, Bugs, Lacking features, IRQ
conflicts, System crashes, Non-functional multitasking, the Y2K problem
and the Blue Screen of Death are registered trademarks of
Microsoft, Corp., Redmond, USA.
--------------------------------- [ moffe at amagerkollegiet dot dk ] --
You can't disable MMX/SSE because its used to optimise, if you don't want
to use SSE/MMX select a non-SSE/MMX cpu in the kernel config, that way
you'll lose those assembly optimisations. If you want to impare your CPU
even more (as seems the case) consider using 486 as a CPU target and perhaps also
cripple your cpu caches (ie set bit 0x1E (CD) in cr0).
Cheers,
Zwane Mwaikambo
"Maciej W. Rozycki" wrote:
>
> On Wed, 21 Nov 2001, Pavel Machek wrote:
>
> > Is there way not to let linux use FPU, MMX, SSE and similar fancy
> > units? I have athlon processor, but would like to turn FPU (and
> > similar fancy stuff) off...
>
> You may use "no387" to disable FPU and MMX (they are controlled by a
> single bit in cr0). No idea about SSE.
Looks to me like another candidate for the setup/bugs/cpuid
processor-type splitting/cleanup that DaveJ et al have mentioned
[for 2.5 ?].
include/asm-i386/bugs.h is the only header file in linux/ that
contains^W hides __setup() parameters, and that's bad IMO.
~Randy