| Message ID | 51181317.1080905@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Len Brown |
| Headers | show |
On Sun, Feb 10, 2013 at 04:37:27PM -0500, Len Brown wrote: > From: Len Brown <len.brown@intel.com> > > 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 > --- > v2: remove also check_hlt() [ … ] > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c > index 3286a92..e280253 100644 > --- a/arch/x86/kernel/cpu/proc.c > +++ b/arch/x86/kernel/cpu/proc.c > @@ -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" Are we fine with changing /proc/cpuinfo output? We tend to consider it an API to userspace, judging by past experience...
Yes... safer that way. Borislav Petkov <bp@alien8.de> wrote: >On Sun, Feb 10, 2013 at 04:37:27PM -0500, Len Brown wrote: >> From: Len Brown <len.brown@intel.com> >> >> 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 >> --- >> v2: remove also check_hlt() > >[ … ] > >> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c >> index 3286a92..e280253 100644 >> --- a/arch/x86/kernel/cpu/proc.c >> +++ b/arch/x86/kernel/cpu/proc.c >> @@ -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" > >Are we fine with changing /proc/cpuinfo output? We tend to consider it >an API to userspace, judging by past experience...
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 3b0cd1e..109ee45 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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. diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 8a28fea..b9e7d27 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -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); diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 92dfec9..af6455e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -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(); diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c index 3286a92..e280253 100644 --- a/arch/x86/kernel/cpu/proc.c +++ b/arch/x86/kernel/cpu/proc.c @@ -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", diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index cd5a4c9..aef852e 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -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(); } /* diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 2b73b5c..94eac5c 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -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());