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| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2007-05-02 19:27:16 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2007-05-02 19:27:16 +0200 |
| commit | 7c3576d261ce046789a7db14f43303f8120910c7 (patch) | |
| tree | ad27a8459bbcdb183fe2411aec3b840942992ad5 /include/asm-i386/segment.h | |
| parent | 7a61d35d4b4056e7711031202da7605e052f4137 (diff) | |
| download | linux-3.10-7c3576d261ce046789a7db14f43303f8120910c7.tar.gz linux-3.10-7c3576d261ce046789a7db14f43303f8120910c7.tar.bz2 linux-3.10-7c3576d261ce046789a7db14f43303f8120910c7.zip | |
[PATCH] i386: Convert PDA into the percpu section
Currently x86 (similar to x84-64) has a special per-cpu structure
called "i386_pda" which can be easily and efficiently referenced via
the %fs register. An ELF section is more flexible than a structure,
allowing any piece of code to use this area. Indeed, such a section
already exists: the per-cpu area.
So this patch:
(1) Removes the PDA and uses per-cpu variables for each current member.
(2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU.
(3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which
can be used to calculate addresses for this CPU's variables.
(4) Simplifies startup, because %fs doesn't need to be loaded with a
special segment at early boot; it can be deferred until the first
percpu area is allocated (or never for UP).
The result is less code and one less x86-specific concept.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-i386/segment.h')
| -rw-r--r-- | include/asm-i386/segment.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h index 065f10bfa48..07e70624d87 100644 --- a/include/asm-i386/segment.h +++ b/include/asm-i386/segment.h @@ -39,7 +39,7 @@ * 25 - APM BIOS support * * 26 - ESPFIX small SS - * 27 - PDA [ per-cpu private data area ] + * 27 - per-cpu [ offset to per-cpu data area ] * 28 - unused * 29 - unused * 30 - unused @@ -74,8 +74,8 @@ #define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE + 14) #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8) -#define GDT_ENTRY_PDA (GDT_ENTRY_KERNEL_BASE + 15) -#define __KERNEL_PDA (GDT_ENTRY_PDA * 8) +#define GDT_ENTRY_PERCPU (GDT_ENTRY_KERNEL_BASE + 15) +#define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8) #define GDT_ENTRY_DOUBLEFAULT_TSS 31 |