The patch titled
Use the APIC to determine the hardware processor id - x86_64
has been added to the -mm tree. Its filename is
use-the-apic-to-determine-the-hardware-processor-id-x86_64.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Use the APIC to determine the hardware processor id - x86_64
From: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
hard_smp_processor_id used to be just a macro that hard-coded
hard_smp_processor_id to 0 in the non SMP case. When booting non SMP kernels
on hardware where the boot ioapic id is not 0 this turns out to be a problem.
This is happens frequently in the case of kdump and once in a great while in
the case of real hardware.
Use the APIC to determine the hardware processor id in both UP and SMP kernels
to fix this issue.
Notice that hard_smp_processor_id is only used by SMP code or by code that
works with apics so we do not need to handle the case when apics are not
present and hard_smp_processor_id should never be called there.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-x86_64/smp.h | 14 ++++++--------
1 files changed, 6 insertions(+), 8 deletions(-)
diff -puN include/asm-x86_64/smp.h~use-the-apic-to-determine-the-hardware-processor-id-x86_64 include/asm-x86_64/smp.h
--- a/include/asm-x86_64/smp.h~use-the-apic-to-determine-the-hardware-processor-id-x86_64
+++ a/include/asm-x86_64/smp.h
@@ -57,12 +57,6 @@ static inline int num_booting_cpus(void)
#define raw_smp_processor_id() read_pda(cpunumber)
-static inline int hard_smp_processor_id(void)
-{
- /* we don't want to mark this access volatile - bad code generation */
- return GET_APIC_ID(*(unsigned int *)(APIC_BASE+APIC_ID));
-}
-
extern int __cpu_disable(void);
extern void __cpu_die(unsigned int cpu);
extern void prefill_possible_map(void);
@@ -71,10 +65,14 @@ extern unsigned __cpuinitdata disabled_c
#define NO_PROC_ID 0xFF /* No processor magic marker */
-#else /* CONFIG_SMP */
-#define hard_smp_processor_id() 0
#endif /* CONFIG_SMP */
+static inline int hard_smp_processor_id(void)
+{
+ /* we don't want to mark this access volatile - bad code generation */
+ return GET_APIC_ID(*(unsigned int *)(APIC_BASE+APIC_ID));
+}
+
/*
* Some lowlevel functions might want to know about
* the real APIC ID <-> CPU # mapping.
_
Patches currently in -mm which might be from fernando@xxxxxxxxxxxxx are
remove-hardcoding-of-hard_smp_processor_id-on-up.patch
use-the-apic-to-determine-the-hardware-processor-id-i386.patch
use-the-apic-to-determine-the-hardware-processor-id-x86_64.patch
always-ask-the-hardware-to-obtain-hardware-processor-id-ia64.patch
-
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