2 * Copyright (C) 1994 Linus Torvalds
4 * Cyrix stuff, June 1998 by:
5 * - Rafael R. Reilova (moved everything from head.S),
6 * <rreilova@ececs.uc.edu>
7 * - Channing Corn (tests & fixes),
8 * - Andrew D. Balsa (code cleanup).
10 #include <linux/init.h>
11 #include <linux/utsname.h>
13 #include <asm/processor.h>
14 #include <asm/processor-flags.h>
17 #include <asm/paravirt.h>
18 #include <asm/alternative.h>
21 static int __init no_halt(char *s)
23 WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
24 boot_cpu_data.hlt_works_ok = 0;
28 __setup("no-hlt", no_halt);
31 static int __init no_387(char *s)
33 boot_cpu_data.hard_math = 0;
34 write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0());
38 __setup("no387", no_387);
40 static double __initdata x = 4195835.0;
41 static double __initdata y = 3145727.0;
44 * This used to check for exceptions..
45 * However, it turns out that to support that,
46 * the XMM trap handlers basically had to
47 * be buggy. So let's have a correct XMM trap
48 * handler, and forget about printing out
49 * some status at boot.
51 * We should really only care about bugs here
52 * anyway. Not features.
54 static void __init check_fpu(void)
58 if (!boot_cpu_data.hard_math) {
59 #ifndef CONFIG_MATH_EMULATION
60 printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
61 printk(KERN_EMERG "Giving up.\n");
70 * trap_init() enabled FXSR and company _before_ testing for FP
73 * Test for the divl bug..
80 "fsubp %%st,%%st(1)\n\t"
85 : "m" (*&x), "m" (*&y));
90 boot_cpu_data.fdiv_bug = fdiv_bug;
91 if (boot_cpu_data.fdiv_bug)
92 printk(KERN_WARNING "Hmm, FPU with FDIV bug.\n");
96 static void __init check_hlt(void)
99 if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
102 printk(KERN_INFO "Checking 'hlt' instruction... ");
103 if (!boot_cpu_data.hlt_works_ok) {
104 printk("disabled\n");
111 printk(KERN_CONT "OK.\n");
116 * Most 386 processors have a bug where a POPAD can lock the
117 * machine even from user space.
120 static void __init check_popad(void)
122 #ifndef CONFIG_X86_POPAD_OK
123 int res, inp = (int) &res;
125 printk(KERN_INFO "Checking for popad bug... ");
126 __asm__ __volatile__(
127 "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
132 * If this fails, it means that any user program may lock the
136 printk(KERN_CONT "Buggy.\n");
138 printk(KERN_CONT "OK.\n");
143 * Check whether we are able to run this kernel safely on SMP.
145 * - In order to run on a i386, we need to be compiled for i386
146 * (for due to lack of "invlpg" and working WP on a i386)
147 * - In order to run on anything without a TSC, we need to be
148 * compiled for a i486.
151 static void __init check_config(void)
154 * We'd better not be a i386 if we're configured to use some
155 * i486+ only features! (WP works in supervisor mode and the
156 * new "invlpg" and "bswap" instructions)
158 #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || \
159 defined(CONFIG_X86_BSWAP)
160 if (boot_cpu_data.x86 == 3)
161 panic("Kernel requires i486+ for 'invlpg' and other features");
166 void __init check_bugs(void)
170 printk(KERN_INFO "CPU: ");
171 print_cpu_info(&boot_cpu_data);
177 init_utsname()->machine[1] =
178 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
179 alternative_instructions();