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| author | Michael Ellerman <michael@ellerman.id.au> | 2010-01-28 13:23:22 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-03-09 11:52:52 +1100 |
| commit | 1426d5a3bd07589534286375998c0c8c6fdc5260 (patch) | |
| tree | fade4f3afd6324b46e27f3c8702935a7edc2fe21 /arch/powerpc/platforms | |
| parent | 59603b9ae426e968d452f9325cdcff308573dee7 (diff) | |
| download | linux-1426d5a3bd07589534286375998c0c8c6fdc5260.tar.gz linux-1426d5a3bd07589534286375998c0c8c6fdc5260.tar.bz2 linux-1426d5a3bd07589534286375998c0c8c6fdc5260.zip | |
powerpc: Dynamically allocate pacas
On 64-bit kernels we currently have a 512 byte struct paca_struct for
each cpu (usually just called "the paca"). Currently they are statically
allocated, which means a kernel built for a large number of cpus will
waste a lot of space if it's booted on a machine with few cpus.
We can avoid that by only allocating the number of pacas we need at
boot. However this is complicated by the fact that we need to access
the paca before we know how many cpus there are in the system.
The solution is to dynamically allocate enough space for NR_CPUS pacas,
but then later in boot when we know how many cpus we have, we free any
unused pacas.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/platforms')
| -rw-r--r-- | arch/powerpc/platforms/iseries/exception.S | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/powerpc/platforms/iseries/exception.S b/arch/powerpc/platforms/iseries/exception.S index 5369653dcf6a..fba5bf915073 100644 --- a/arch/powerpc/platforms/iseries/exception.S +++ b/arch/powerpc/platforms/iseries/exception.S @@ -43,17 +43,14 @@ system_reset_iSeries: LOAD_REG_ADDR(r23, alpaca) li r0,ALPACA_SIZE sub r23,r13,r23 - divdu r23,r23,r0 /* r23 has cpu number */ - LOAD_REG_ADDR(r13, paca) - mulli r0,r23,PACA_SIZE - add r13,r13,r0 - mtspr SPRN_SPRG_PACA,r13 /* Save it away for the future */ - mfmsr r24 - ori r24,r24,MSR_RI - mtmsrd r24 /* RI on */ - mr r24,r23 + divdu r24,r23,r0 /* r24 has cpu number */ cmpwi 0,r24,0 /* Are we processor 0? */ bne 1f + LOAD_REG_ADDR(r13, boot_paca) + mtspr SPRN_SPRG_PACA,r13 /* Save it away for the future */ + mfmsr r23 + ori r23,r23,MSR_RI + mtmsrd r23 /* RI on */ b .__start_initialization_iSeries /* Start up the first processor */ 1: mfspr r4,SPRN_CTRLF li r5,CTRL_RUNLATCH /* Turn off the run light */ @@ -86,6 +83,16 @@ system_reset_iSeries: #endif 2: + /* Load our paca now that it's been allocated */ + LOAD_REG_ADDR(r13, paca) + ld r13,0(r13) + mulli r0,r24,PACA_SIZE + add r13,r13,r0 + mtspr SPRN_SPRG_PACA,r13 /* Save it away for the future */ + mfmsr r23 + ori r23,r23,MSR_RI + mtmsrd r23 /* RI on */ + HMT_LOW #ifdef CONFIG_SMP lbz r23,PACAPROCSTART(r13) /* Test if this processor |