Messages in this thread | | | Date | Fri, 31 Oct 1997 18:38:53 +0100 (MET) | From | root <> | Subject | Re[2]: Kernels 2.1 with 386DX/387 IRQ13 PC boxes |
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Hi,
Sorry for replying once for different people, but here is what I'd like to say :
Alan wrote: >> I have a problem with kernels since at least 2.1.46 and up to 2.1.59 >> with my 386DX33 (AMD compatible) and my 387 Cyrix FasMath CX83D87-33 GP >> math coprocessor. I think the problem appears also with a standart >> Intel 80386/80387 when IRQ13 is used. > >Turn off the SMP=1 in the top Makefile
OK, but if 386/387 IRQ13 PC can work with SMP defined, why not to correct the kernel? I do not think it is easy to maintain 4 linux kernels, taking into account that there is already the developpement tree and the stable one.
>> Then, the kernel will boot ONLY if SMP is NOT defined at compile >> time. > >Correct - IRQ 13 does something totally different in SMP mode. (BTW if >someone is crazy enough to want to work on this some IBM dual 486 boards >have 486SLC + FPU delivering a local IRQ 13 to each CPU) - we dont >support that either
The IRQ13 synchronisation mecanism is not used for SMP (line 376 of traps.c), and now an IRQ13 always call the math_error function or returns.
John Gotts wrotes : >In any case, you should not be running an SMP kernel on a non-SMP >machine. It isn't guaranteed to work and certainly it won't perform as >well as a uniprocessor kernel in your configuration.
I also have a 2.0.31 kernel running, but to try developpments, why not to use the lattest kernel ? Also maintainning 4 versions is difficult, as previously stated.
Gabriel wrotes: >unsigned short cw=0x340; >asm volatile("fninit; fldcw %0; fld %%st; wait": : "m" (cw)); and >main() { > unsigned short cw; > asm("fstcw %0": "=m" (cw):); > printf("Initial FPU CW:%x\n", cw); >}
Thanks, that is working and I will do more test. I just wonder why this control word is not set when a program set a handler for SIGFPE (signal() function) ?
Thanks for everyone, Etienne.
-- Personnal E-mail : etienne.lorrain@ibm.net ------------- On ne voit bien qu'avec le coeur, -------------------- ----- l'essentiel est invisible pour les yeux . St Exupery ---------
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