Commit-ID: f1ccd249319efca4ee4faf1d904f5a362cac7c81
Gitweb: http://git.kernel.org/tip/f1ccd249319efca4ee4faf1d904f5a362cac7c81
Author: Len Brown <len.brown@xxxxxxxxx>
AuthorDate: Fri, 16 Oct 2015 00:14:28 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 19 Oct 2015 09:14:41 +0200
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@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: dparsons@xxxxxxxxxxxxx
Cc: shrybman@xxxxxxxxxxxx
Link: http://lkml.kernel.org/r/de363cdbbcfcca1d22569683f7eb9873e0177251.1444968087.git.len.brown@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/smpboot.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index e0c198e..32267cc 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;
}
/*
--
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