2005-09-08 15:17:01

by Jan Beulich

[permalink] [raw]

Subject: [PATCH] move i386's enabling of fxsr and xmmxcpt

---

(Note: Patch also attached because the inline version is certain to get
line wrapped.)

Move some code unrelated to any dealing with hardware bugs from i386's
bugs.h to a more logical place.

Signed-off-by: Jan Beulich <[email protected]>

diff -Npru 2.6.13/arch/i386/kernel/traps.c
2.6.13-i386-fxsr/arch/i386/kernel/traps.c
--- 2.6.13/arch/i386/kernel/traps.c 2005-08-29 01:41:01.000000000
+0200
+++ 2.6.13-i386-fxsr/arch/i386/kernel/traps.c 2005-09-07
11:46:35.000000000 +0200
@@ -1098,6 +1098,24 @@ void __init trap_init(void)
#endif
set_trap_gate(19,&simd_coprocessor_error);

+ if (cpu_has_fxsr) {
+ /*
+ * Verify that the FXSAVE/FXRSTOR data will be 16-byte
aligned.
+ */
+ struct fxsrAlignAssert {
+ int _:!(offsetof(struct task_struct,
thread.i387.fxsave) & 15);
+ };
+
+ printk(KERN_INFO "Enabling fast FPU save and restore...
");
+ set_in_cr4(X86_CR4_OSFXSR);
+ printk("done.\n");
+ }
+ if (cpu_has_xmm) {
+ printk(KERN_INFO "Enabling unmasked SIMD FPU exception
support... ");
+ set_in_cr4(X86_CR4_OSXMMEXCPT);
+ printk("done.\n");
+ }
+
set_system_gate(SYSCALL_VECTOR,&system_call);

/*
diff -Npru 2.6.13/include/asm-i386/bugs.h
2.6.13-i386-fxsr/include/asm-i386/bugs.h
--- 2.6.13/include/asm-i386/bugs.h 2005-08-29 01:41:01.000000000
+0200
+++ 2.6.13-i386-fxsr/include/asm-i386/bugs.h 2005-09-01
11:32:11.000000000 +0200
@@ -8,9 +8,6 @@
* <[email protected]>
* - Channing Corn (tests & fixes),
* - Andrew D. Balsa (code cleanup).
- *
- * Pentium III FXSR, SSE support
- * Gareth Hughes <[email protected]>, May 2000
*/

/*
@@ -76,25 +73,7 @@ static void __init check_fpu(void)
return;
}

-/* Enable FXSR and company _before_ testing for FP problems. */
- /*
- * Verify that the FXSAVE/FXRSTOR data will be 16-byte aligned.
- */
- if (offsetof(struct task_struct, thread.i387.fxsave) & 15) {
- extern void __buggy_fxsr_alignment(void);
- __buggy_fxsr_alignment();
- }
- if (cpu_has_fxsr) {
- printk(KERN_INFO "Enabling fast FPU save and restore...
");
- set_in_cr4(X86_CR4_OSFXSR);
- printk("done.\n");
- }
- if (cpu_has_xmm) {
- printk(KERN_INFO "Enabling unmasked SIMD FPU exception
support... ");
- set_in_cr4(X86_CR4_OSXMMEXCPT);
- printk("done.\n");
- }
-
+/* trap_init() enabled FXSR and company _before_ testing for FP
problems here. */
/* Test for the divl bug.. */
__asm__("fninit\n\t"
"fldl %1\n\t"

---

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2005-09-08 17:51:52

by Zwane Mwaikambo

[permalink] [raw]

Subject: Re: [PATCH] move i386's enabling of fxsr and xmmxcpt

---

On Thu, 8 Sep 2005, Jan Beulich wrote:

> (Note: Patch also attached because the inline version is certain to get
> line wrapped.)
>
> Move some code unrelated to any dealing with hardware bugs from i386's
> bugs.h to a more logical place.
>
> Signed-off-by: Jan Beulich <[email protected]>
>
> diff -Npru 2.6.13/arch/i386/kernel/traps.c
> 2.6.13-i386-fxsr/arch/i386/kernel/traps.c
> --- 2.6.13/arch/i386/kernel/traps.c 2005-08-29 01:41:01.000000000
> +0200
> +++ 2.6.13-i386-fxsr/arch/i386/kernel/traps.c 2005-09-07
> 11:46:35.000000000 +0200
> @@ -1098,6 +1098,24 @@ void __init trap_init(void)
> #endif
> set_trap_gate(19,&simd_coprocessor_error);
>
> + if (cpu_has_fxsr) {
> + /*
> + * Verify that the FXSAVE/FXRSTOR data will be 16-byte
> aligned.
> + */
> + struct fxsrAlignAssert {
> + int _:!(offsetof(struct task_struct,
> thread.i387.fxsave) & 15);
> + };
> +
> + printk(KERN_INFO "Enabling fast FPU save and restore...
> ");
> + set_in_cr4(X86_CR4_OSFXSR);
> + printk("done.\n");
> + }
> + if (cpu_has_xmm) {
> + printk(KERN_INFO "Enabling unmasked SIMD FPU exception
> support... ");
> + set_in_cr4(X86_CR4_OSXMMEXCPT);
> + printk("done.\n");
> + }
> +
> set_system_gate(SYSCALL_VECTOR,&system_call);

Hmm doesn't this really belong in identify_cpu()?