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authorLen Brown <len.brown@intel.com>2015-10-16 00:14:28 -0400
committerIngo Molnar <mingo@kernel.org>2015-10-19 09:14:41 +0200
commitf1ccd249319efca4ee4faf1d904f5a362cac7c81 (patch)
treec92f1785121f3c0973c4627c15435688be336d91 /arch
parentc0ff971ef9acacd4d2caa508e444edad958dead9 (diff)
downloadlinux-f1ccd249319efca4ee4faf1d904f5a362cac7c81.tar.bz2
x86/smpboot: Fix cpu_init_udelay=10000 corner case boot parameter misbehavior
For legacy machines cpu_init_udelay defaults to 10,000. For modern machines it is set to 0. The user should be able to set cpu_init_udelay to any value on the cmdline, including 10,000. Before this patch, that was seen as "unchanged from default" and thus on a modern machine, the user request was ignored and the delay was set to 0. Signed-off-by: Len Brown <len.brown@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dparsons@brightdsl.net Cc: shrybman@teksavvy.com Link: http://lkml.kernel.org/r/de363cdbbcfcca1d22569683f7eb9873e0177251.1444968087.git.len.brown@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/smpboot.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index e0c198e5f920..32267ccac3d7 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -509,7 +509,7 @@ void __inquire_remote_apic(int apicid)
*/
#define UDELAY_10MS_DEFAULT 10000
-static unsigned int init_udelay = UDELAY_10MS_DEFAULT;
+static unsigned int init_udelay = INT_MAX;
static int __init cpu_init_udelay(char *str)
{
@@ -522,13 +522,16 @@ early_param("cpu_init_udelay", cpu_init_udelay);
static void __init smp_quirk_init_udelay(void)
{
/* if cmdline changed it from default, leave it alone */
- if (init_udelay != UDELAY_10MS_DEFAULT)
+ if (init_udelay != INT_MAX)
return;
/* if modern processor, use no delay */
if (((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 6)) ||
((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (boot_cpu_data.x86 >= 0xF)))
init_udelay = 0;
+
+ /* else, use legacy delay */
+ init_udelay = UDELAY_10MS_DEFAULT;
}
/*