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SubjectAPIC, AMD-K6/2 -mcpu=586...


I have the 2.4.4 distribution from


I have a Mandrake system and selected the AMD processors and APIC
option. The egcs-2.91.66 compiler with -mcpu=586. It appears that
the structure alignment of the floating point registers was not
correct under this configuration. This code was being compiled and
a linker error produced.

if (offsetof(struct task_struct, thread.i387.fxsave) & 15) {
/* printk("WJP: value is %x.\n",
offsetof(struct task_struct, thread.i387.fxsave) & 15); */
/* while(1); */
extern void __buggy_fxsr_alignment(void);

The alignment was to 8 bytes instead of 16. I added some padding to
the thread structure to produce an alignment of 16 and the code
compiled and seemed to work fine; I used it for a few days.

[in processor.h]
/* floating point info */
/* unsigned char wjpDummy[8]; */
union i387_union i387;

I did not see any mention of this in the archives [but the volume of
mailings is large... which I may be contributing to]. I recompiled
without the padding and APIC support and everything seems to be fine,
but _VERY_ slow. Is this change ok locally? Has it been addressed
in a patch?

Bill Pringlemeir.

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