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>
20 static int __init
no_halt(char *s
)
22 WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
23 boot_cpu_data
.hlt_works_ok
= 0;
27 __setup("no-hlt", no_halt
);
29 static int __init
no_387(char *s
)
31 boot_cpu_data
.hard_math
= 0;
32 write_cr0(X86_CR0_TS
| X86_CR0_EM
| X86_CR0_MP
| read_cr0());
36 __setup("no387", no_387
);
38 static double __initdata x
= 4195835.0;
39 static double __initdata y
= 3145727.0;
42 * This used to check for exceptions..
43 * However, it turns out that to support that,
44 * the XMM trap handlers basically had to
45 * be buggy. So let's have a correct XMM trap
46 * handler, and forget about printing out
47 * some status at boot.
49 * We should really only care about bugs here
50 * anyway. Not features.
52 static void __init
check_fpu(void)
56 if (!boot_cpu_data
.hard_math
) {
57 #ifndef CONFIG_MATH_EMULATION
58 printk(KERN_EMERG
"No coprocessor found and no math emulation present.\n");
59 printk(KERN_EMERG
"Giving up.\n");
66 * trap_init() enabled FXSR and company _before_ testing for FP
69 * Test for the divl bug..
76 "fsubp %%st,%%st(1)\n\t"
81 : "m" (*&x
), "m" (*&y
));
83 boot_cpu_data
.fdiv_bug
= fdiv_bug
;
84 if (boot_cpu_data
.fdiv_bug
)
85 printk(KERN_WARNING
"Hmm, FPU with FDIV bug.\n");
88 static void __init
check_hlt(void)
90 if (boot_cpu_data
.x86
>= 5 || paravirt_enabled())
93 printk(KERN_INFO
"Checking 'hlt' instruction... ");
94 if (!boot_cpu_data
.hlt_works_ok
) {
102 printk(KERN_CONT
"OK.\n");
106 * Most 386 processors have a bug where a POPAD can lock the
107 * machine even from user space.
110 static void __init
check_popad(void)
112 #ifndef CONFIG_X86_POPAD_OK
113 int res
, inp
= (int) &res
;
115 printk(KERN_INFO
"Checking for popad bug... ");
116 __asm__
__volatile__(
117 "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
122 * If this fails, it means that any user program may lock the
126 printk(KERN_CONT
"Buggy.\n");
128 printk(KERN_CONT
"OK.\n");
133 * Check whether we are able to run this kernel safely on SMP.
135 * - In order to run on a i386, we need to be compiled for i386
136 * (for due to lack of "invlpg" and working WP on a i386)
137 * - In order to run on anything without a TSC, we need to be
138 * compiled for a i486.
141 static void __init
check_config(void)
144 * We'd better not be a i386 if we're configured to use some
145 * i486+ only features! (WP works in supervisor mode and the
146 * new "invlpg" and "bswap" instructions)
148 #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || \
149 defined(CONFIG_X86_BSWAP)
150 if (boot_cpu_data
.x86
== 3)
151 panic("Kernel requires i486+ for 'invlpg' and other features");
156 void __init
check_bugs(void)
160 printk(KERN_INFO
"CPU: ");
161 print_cpu_info(&boot_cpu_data
);
167 init_utsname()->machine
[1] =
168 '0' + (boot_cpu_data
.x86
> 6 ? 6 : boot_cpu_data
.x86
);
169 alternative_instructions();