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2a9e4ee5904d50b91d3b6310ed2e78451ce2630c
2 * include/asm-i386/bugs.h
4 * Copyright (C) 1994 Linus Torvalds
6 * Cyrix stuff, June 1998 by:
7 * - Rafael R. Reilova (moved everything from head.S),
8 * <rreilova@ececs.uc.edu>
9 * - Channing Corn (tests & fixes),
10 * - Andrew D. Balsa (code cleanup).
14 * This is included by init/main.c to check for architecture-dependent bugs.
17 * void check_bugs(void);
20 #include <linux/init.h>
21 #include <asm/processor.h>
25 static int __init
no_halt(char *s
)
27 boot_cpu_data
.hlt_works_ok
= 0;
31 __setup("no-hlt", no_halt
);
33 static int __init
mca_pentium(char *s
)
39 __setup("mca-pentium", mca_pentium
);
41 static int __init
no_387(char *s
)
43 boot_cpu_data
.hard_math
= 0;
44 write_cr0(0xE | read_cr0());
48 __setup("no387", no_387
);
50 static double __initdata x
= 4195835.0;
51 static double __initdata y
= 3145727.0;
54 * This used to check for exceptions..
55 * However, it turns out that to support that,
56 * the XMM trap handlers basically had to
57 * be buggy. So let's have a correct XMM trap
58 * handler, and forget about printing out
59 * some status at boot.
61 * We should really only care about bugs here
62 * anyway. Not features.
64 static void __init
check_fpu(void)
66 if (!boot_cpu_data
.hard_math
) {
67 #ifndef CONFIG_MATH_EMULATION
68 printk(KERN_EMERG
"No coprocessor found and no math emulation present.\n");
69 printk(KERN_EMERG
"Giving up.\n");
75 /* trap_init() enabled FXSR and company _before_ testing for FP problems here. */
76 /* Test for the divl bug.. */
82 "fsubp %%st,%%st(1)\n\t"
86 : "=m" (*&boot_cpu_data
.fdiv_bug
)
87 : "m" (*&x
), "m" (*&y
));
88 if (boot_cpu_data
.fdiv_bug
)
89 printk("Hmm, FPU with FDIV bug.\n");
92 static void __init
check_hlt(void)
94 printk(KERN_INFO
"Checking 'hlt' instruction... ");
95 if (!boot_cpu_data
.hlt_works_ok
) {
107 * Most 386 processors have a bug where a POPAD can lock the
108 * machine even from user space.
111 static void __init
check_popad(void)
113 #ifndef CONFIG_X86_POPAD_OK
114 int res
, inp
= (int) &res
;
116 printk(KERN_INFO
"Checking for popad bug... ");
117 __asm__
__volatile__(
118 "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 CPU hard. Too bad. */
123 if (res
!= 12345678) printk( "Buggy.\n" );
124 else printk( "OK.\n" );
129 * Check whether we are able to run this kernel safely on SMP.
131 * - In order to run on a i386, we need to be compiled for i386
132 * (for due to lack of "invlpg" and working WP on a i386)
133 * - In order to run on anything without a TSC, we need to be
134 * compiled for a i486.
135 * - In order to support the local APIC on a buggy Pentium machine,
136 * we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
137 * which happens implicitly if compiled for a Pentium or lower
138 * (unless an advanced selection of CPU features is used) as an
139 * otherwise config implies a properly working local APIC without
140 * the need to do extra reads from the APIC.
143 static void __init
check_config(void)
146 * We'd better not be a i386 if we're configured to use some
147 * i486+ only features! (WP works in supervisor mode and the
148 * new "invlpg" and "bswap" instructions)
150 #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_BSWAP)
151 if (boot_cpu_data
.x86
== 3)
152 panic("Kernel requires i486+ for 'invlpg' and other features");
156 * If we configured ourselves for a TSC, we'd better have one!
158 #ifdef CONFIG_X86_TSC
160 panic("Kernel compiled for Pentium+, requires TSC feature!");
164 * If we were told we had a good local APIC, check for buggy Pentia,
165 * i.e. all B steppings and the C2 stepping of P54C when using their
166 * integrated APIC (see 11AP erratum in "Pentium Processor
167 * Specification Update").
169 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
170 if (boot_cpu_data
.x86_vendor
== X86_VENDOR_INTEL
172 && boot_cpu_data
.x86
== 5
173 && boot_cpu_data
.x86_model
== 2
174 && (boot_cpu_data
.x86_mask
< 6 || boot_cpu_data
.x86_mask
== 11))
175 panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
179 extern void alternative_instructions(void);
181 static void __init
check_bugs(void)
183 identify_cpu(&boot_cpu_data
);
186 print_cpu_info(&boot_cpu_data
);
192 system_utsname
.machine
[1] = '0' + (boot_cpu_data
.x86
> 6 ? 6 : boot_cpu_data
.x86
);
193 alternative_instructions();