On Sun, Jan 30, 2011 at 04:27:55PM +0000, Will Deacon wrote: > > mrc p15, 0, r0, c0, c0, 5 @ read MPIDR > > > The code following this does: > > tst r0, #1 << 31 > movne pc, lr @ bit 31 => SMP > > As an optimisation, we could also check that bit 30 is zero so that > we patch out the SMP stuff for single-core A5/A9/A15. Up to you. Ok, so with that added, it becomes: arch/arm/kernel/head.S | 22 ++++++++++------------ 1 files changed, 10 insertions(+), 12 deletions(-) diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index f17d9a0..c0225da 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -392,24 +392,22 @@ ENDPROC(__turn_mmu_on) #ifdef CONFIG_SMP_ON_UP __fixup_smp: - mov r4, #0x00070000 - orr r3, r4, #0xff000000 @ mask 0xff070000 - orr r4, r4, #0x41000000 @ val 0x41070000 - and r0, r9, r3 - teq r0, r4 @ ARM CPU and ARMv6/v7? + and r3, r9, #0x000f0000 @ architecture version + teq r3, #0x000f0000 @ CPU ID supported? bne __fixup_smp_on_up @ no, assume UP - orr r3, r3, #0x0000ff00 - orr r3, r3, #0x000000f0 @ mask 0xff07fff0 + bic r3, r9, #0x00ff0000 + bic r3, r3, #0x0000000f @ mask 0xff00fff0 + mov r4, #0x41000000 orr r4, r4, #0x0000b000 - orr r4, r4, #0x00000020 @ val 0x4107b020 - and r0, r9, r3 - teq r0, r4 @ ARM 11MPCore? + orr r4, r4, #0x00000020 @ val 0x4100b020 + teq r3, r4 @ ARM 11MPCore? moveq pc, lr @ yes, assume SMP mrc p15, 0, r0, c0, c0, 5 @ read MPIDR - tst r0, #1 << 31 - movne pc, lr @ bit 31 => SMP + and r0, r0, #0xc0000000 @ multiprocessing extensions and + teq r0, #0x80000000 @ not part of a uniprocessor system? + moveq pc, lr @ yes, assume SMP __fixup_smp_on_up: adr r0, 1f -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
