On Mon, Sep 12, 2011 at 9:52 AM, Dave Martin <dave.martin@xxxxxxxxxx> wrote: > Colin, can you comment on this? > > On Wed, Sep 07, 2011 at 05:00:53PM +0100, Dave Martin wrote: >> At secondary_startup, the MSR CPSR_cxsf, #0xd3 is not compatible >> with Thumb-2 and also unmasks asynchronous aborts (CPSR.A bit >> forced to zero -- this is probably unintentional). >> >> Any remotely sane bootloader should be putting each secondary CPU >> in the appropriate state _before_ entering the kernel anyway. >> Otherwise, disabling interrupts on entry to the kernel isn't going >> to fix it. >> >> Therefore this patch just removes the MSR instruction. >> >> Signed-off-by: Dave Martin <dave.martin@xxxxxxxxxx> >> --- >> >> I make assumptions about the bootloader in this patch. If someone with >> Tegra knowledge can please comment and/or test, that would be much >> appreciated, thanks. >> >> arch/arm/mach-tegra/headsmp.S | 1 - >> 1 files changed, 0 insertions(+), 1 deletions(-) >> >> diff --git a/arch/arm/mach-tegra/headsmp.S b/arch/arm/mach-tegra/headsmp.S >> index b5349b2..6ec4790 100644 >> --- a/arch/arm/mach-tegra/headsmp.S >> +++ b/arch/arm/mach-tegra/headsmp.S >> @@ -48,7 +48,6 @@ ENTRY(v7_invalidate_l1) >> ENDPROC(v7_invalidate_l1) >> >> ENTRY(tegra_secondary_startup) >> - msr cpsr_fsxc, #0xd3 >> bl v7_invalidate_l1 >> mrc p15, 0, r0, c0, c0, 5 >> and r0, r0, #15 > > My rationale here is that the CPU boots straight into the > correct mode -- if there is any boot code before we get here, > then it should already have established the correct mode, otherwise > we're likely to get problems which "MSR" by itself isn't going to > fix -- such as stray interrupts for example. > > If that feels unsafe however, we should still to be able to write > > cpsid aif, #SVC_MODE > > (which is the compact v6/v7-compatible way to set all the interrupt > mask bits and get into a specific mode) Tegra boots with one cpu enabled, and the other in reset. The cpu needs to be initialized from scratch by the kernel. Does cpsid aif, #SVC_MODE compile to the same instruction as the msr instruction? -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
