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https://github.com/torvalds/linux
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27be457000
Remove 32-bit x86 a cmdline param "no-hlt", and the cpuinfo_x86.hlt_works_ok that it sets. If a user wants to avoid HLT, then "idle=poll" is much more useful, as it avoids invocation of HLT in idle, while "no-hlt" failed to do so. Indeed, hlt_works_ok was consulted in only 3 places. First, in /proc/cpuinfo where "hlt_bug yes" would be printed if and only if the user booted the system with "no-hlt" -- as there was no other code to set that flag. Second, check_hlt() would not invoke halt() if "no-hlt" were on the cmdline. Third, it was consulted in stop_this_cpu(), which is invoked by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() -- all cases where the machine is being shutdown/reset. The flag was not consulted in the more frequently invoked play_dead()/hlt_play_dead() used in processor offline and suspend. Since Linux-3.0 there has been a run-time notice upon "no-hlt" invocations indicating that it would be removed in 2012. Signed-off-by: Len Brown <len.brown@intel.com> Cc: x86@kernel.org
116 lines
2.4 KiB
C
116 lines
2.4 KiB
C
/*
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* Copyright (C) 1994 Linus Torvalds
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*
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* Cyrix stuff, June 1998 by:
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* - Rafael R. Reilova (moved everything from head.S),
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* <rreilova@ececs.uc.edu>
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* - Channing Corn (tests & fixes),
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* - Andrew D. Balsa (code cleanup).
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*/
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#include <linux/init.h>
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#include <linux/utsname.h>
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#include <asm/bugs.h>
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#include <asm/processor.h>
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#include <asm/processor-flags.h>
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#include <asm/i387.h>
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#include <asm/msr.h>
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#include <asm/paravirt.h>
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#include <asm/alternative.h>
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static int __init no_387(char *s)
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{
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boot_cpu_data.hard_math = 0;
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write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0());
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return 1;
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}
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__setup("no387", no_387);
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static double __initdata x = 4195835.0;
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static double __initdata y = 3145727.0;
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/*
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* This used to check for exceptions..
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* However, it turns out that to support that,
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* the XMM trap handlers basically had to
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* be buggy. So let's have a correct XMM trap
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* handler, and forget about printing out
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* some status at boot.
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*
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* We should really only care about bugs here
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* anyway. Not features.
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*/
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static void __init check_fpu(void)
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{
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s32 fdiv_bug;
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if (!boot_cpu_data.hard_math) {
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#ifndef CONFIG_MATH_EMULATION
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pr_emerg("No coprocessor found and no math emulation present\n");
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pr_emerg("Giving up\n");
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for (;;) ;
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#endif
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return;
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}
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kernel_fpu_begin();
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/*
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* trap_init() enabled FXSR and company _before_ testing for FP
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* problems here.
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*
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* Test for the divl bug..
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*/
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__asm__("fninit\n\t"
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"fldl %1\n\t"
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"fdivl %2\n\t"
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"fmull %2\n\t"
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"fldl %1\n\t"
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"fsubp %%st,%%st(1)\n\t"
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"fistpl %0\n\t"
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"fwait\n\t"
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"fninit"
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: "=m" (*&fdiv_bug)
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: "m" (*&x), "m" (*&y));
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kernel_fpu_end();
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boot_cpu_data.fdiv_bug = fdiv_bug;
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if (boot_cpu_data.fdiv_bug)
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pr_warn("Hmm, FPU with FDIV bug\n");
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}
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/*
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* Check whether we are able to run this kernel safely on SMP.
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*
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* - i386 is no longer supported.
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* - In order to run on anything without a TSC, we need to be
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* compiled for a i486.
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*/
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static void __init check_config(void)
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{
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if (boot_cpu_data.x86 < 4)
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panic("Kernel requires i486+ for 'invlpg' and other features");
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}
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void __init check_bugs(void)
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{
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identify_boot_cpu();
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#ifndef CONFIG_SMP
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pr_info("CPU: ");
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print_cpu_info(&boot_cpu_data);
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#endif
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check_config();
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init_utsname()->machine[1] =
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'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
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alternative_instructions();
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/*
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* kernel_fpu_begin/end() in check_fpu() relies on the patched
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* alternative instructions.
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*/
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check_fpu();
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}
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