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x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag

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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
This commit is contained in:
Len Brown 2013-02-10 02:28:46 -05:00
parent 69fb3676df
commit 27be457000
6 changed files with 2 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/kernel-parameters.txt
View File

@ -1881,10 +1881,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
no-hlt [BUGS=X86-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
no_file_caps Tells the kernel not to honor file capabilities. The
only way then for a file to be executed with privilege
is to be setuid root or executed by root.

10
arch/x86/include/asm/processor.h
View File

@ -89,7 +89,6 @@ struct cpuinfo_x86 {
char wp_works_ok; /* It doesn't on 386's */
/* Problems on some 486Dx4's and old 386's: */
char hlt_works_ok;
char hard_math;
char rfu;
char fdiv_bug;
@ -165,15 +164,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
extern const struct seq_operations cpuinfo_op;
static inline int hlt_works(int cpu)
{
#ifdef CONFIG_X86_32
return cpu_data(cpu).hlt_works_ok;
#else
return 1;
#endif
}
#define cache_line_size() (boot_cpu_data.x86_cache_alignment)
extern void cpu_detect(struct cpuinfo_x86 *c);

27
arch/x86/kernel/cpu/bugs.c
View File

@ -17,15 +17,6 @@
#include <asm/paravirt.h>
#include <asm/alternative.h>
static int __init no_halt(char *s)
{
WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
boot_cpu_data.hlt_works_ok = 0;
return 1;
}
__setup("no-hlt", no_halt);
static int __init no_387(char *s)
{
boot_cpu_data.hard_math = 0;
@ -89,23 +80,6 @@ static void __init check_fpu(void)
pr_warn("Hmm, FPU with FDIV bug\n");
}
static void __init check_hlt(void)
{
if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
return;
pr_info("Checking 'hlt' instruction... ");
if (!boot_cpu_data.hlt_works_ok) {
pr_cont("disabled\n");
return;
}
halt();
halt();
halt();
halt();
pr_cont("OK\n");
}
/*
* Check whether we are able to run this kernel safely on SMP.
*
@ -129,7 +103,6 @@ void __init check_bugs(void)
print_cpu_info(&boot_cpu_data);
#endif
check_config();
check_hlt();
init_utsname()->machine[1] =
'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
alternative_instructions();

2
arch/x86/kernel/cpu/proc.c
View File

@ -28,7 +28,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
{
seq_printf(m,
"fdiv_bug\t: %s\n"
"hlt_bug\t\t: %s\n"
"f00f_bug\t: %s\n"
"coma_bug\t: %s\n"
"fpu\t\t: %s\n"
@ -36,7 +35,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
"cpuid level\t: %d\n"
"wp\t\t: %s\n",
c->fdiv_bug ? "yes" : "no",
c->hlt_works_ok ? "no" : "yes",
c->f00f_bug ? "yes" : "no",
c->coma_bug ? "yes" : "no",
c->hard_math ? "yes" : "no",

6
arch/x86/kernel/process.c
View File

@ -415,10 +415,8 @@ void stop_this_cpu(void *dummy)
set_cpu_online(smp_processor_id(), false);
disable_local_APIC();
for (;;) {
if (hlt_works(smp_processor_id()))
halt();
}
for (;;)
halt();
}
/*

3
arch/x86/xen/setup.c
View File

@ -556,9 +556,6 @@ void __init xen_arch_setup(void)
COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
/* Set up idle, making sure it calls safe_halt() pvop */
#ifdef CONFIG_X86_32
boot_cpu_data.hlt_works_ok = 1;
#endif
disable_cpuidle();
disable_cpufreq();
WARN_ON(xen_set_default_idle());