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- /*
- * Copyright (C) 1994 Linus Torvalds
- *
- * Cyrix stuff, June 1998 by:
- * - Rafael R. Reilova (moved everything from head.S),
- * <rreilova@ececs.uc.edu>
- * - Channing Corn (tests & fixes),
- * - Andrew D. Balsa (code cleanup).
- */
- #include <linux/init.h>
- #include <linux/utsname.h>
- #include <asm/bugs.h>
- #include <asm/processor.h>
- #include <asm/processor-flags.h>
- #include <asm/i387.h>
- #include <asm/msr.h>
- #include <asm/paravirt.h>
- #include <asm/alternative.h>
- static double __initdata x = 4195835.0;
- static double __initdata y = 3145727.0;
- /*
- * This used to check for exceptions..
- * However, it turns out that to support that,
- * the XMM trap handlers basically had to
- * be buggy. So let's have a correct XMM trap
- * handler, and forget about printing out
- * some status at boot.
- *
- * We should really only care about bugs here
- * anyway. Not features.
- */
- static void __init check_fpu(void)
- {
- s32 fdiv_bug;
- kernel_fpu_begin();
- /*
- * trap_init() enabled FXSR and company _before_ testing for FP
- * problems here.
- *
- * Test for the divl bug: http://en.wikipedia.org/wiki/Fdiv_bug
- */
- __asm__("fninit\n\t"
- "fldl %1\n\t"
- "fdivl %2\n\t"
- "fmull %2\n\t"
- "fldl %1\n\t"
- "fsubp %%st,%%st(1)\n\t"
- "fistpl %0\n\t"
- "fwait\n\t"
- "fninit"
- : "=m" (*&fdiv_bug)
- : "m" (*&x), "m" (*&y));
- kernel_fpu_end();
- if (fdiv_bug) {
- set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
- pr_warn("Hmm, FPU with FDIV bug\n");
- }
- }
- void __init check_bugs(void)
- {
- identify_boot_cpu();
- #ifndef CONFIG_SMP
- pr_info("CPU: ");
- print_cpu_info(&boot_cpu_data);
- #endif
- /*
- * Check whether we are able to run this kernel safely on SMP.
- *
- * - i386 is no longer supported.
- * - In order to run on anything without a TSC, we need to be
- * compiled for a i486.
- */
- if (boot_cpu_data.x86 < 4)
- panic("Kernel requires i486+ for 'invlpg' and other features");
- init_utsname()->machine[1] =
- '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
- alternative_instructions();
- /*
- * kernel_fpu_begin/end() in check_fpu() relies on the patched
- * alternative instructions.
- */
- if (cpu_has_fpu)
- check_fpu();
- }
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