Re: [PATCH v2 2/2] MIPS: CPS: Copy EVA configuration when starting secondary VPs.

[Matt Redfearn]

Hi Paul,

On 18/05/16 23:34, Paul Burton wrote:
> On Wed, May 18, 2016 at 05:12:36PM +0100, Matt Redfearn wrote:
> > When starting secondary VPEs which support EVA and the SegCtl registers,
> > copy the memory segmentation configuration from the running VPE to ensure
> > that all VPEs in the core have a consistent virtual memory map.
> >
> > The EVA configuration of secondary cores is dealt with when starting the
> > core via the CM.
> >
> > Signed-off-by: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
> > ---
> >
> > Changes in v2:
> > - Skip check for config3 existing - we know it must to be doing
> > multithreading
> > - Use a unique lable name in the function
> >
> >   arch/mips/kernel/cps-vec.S | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> >
> > diff --git a/arch/mips/kernel/cps-vec.S b/arch/mips/kernel/cps-vec.S
> > index ac81edd44563..f8eae9189e38 100644
> > --- a/arch/mips/kernel/cps-vec.S
> > +++ b/arch/mips/kernel/cps-vec.S
> > @@ -431,6 +431,21 @@ LEAF(mips_cps_boot_vpes)
> >   	mfc0	t0, CP0_CONFIG
> >   	mttc0	t0, CP0_CONFIG
> >   
> > +	/*
> > +	 * Copy the EVA config from this VPE if the CPU supports it.
> > +	 * CONFIG3 must exist to be running MT startup - just read it.
> > +	 */
> > +	mfc0	t0, CP0_CONFIG, 3
> > +	and	t0, t0, MIPS_CONF3_SC
> Tiny nit - I'd prefer "andi" here since we're using an immediate. The
> assembler will figure it out though, so it's not a big deal.
Yeah, I would have too, and I did have that to start off with, but the 
assembler gave me:
arch/mips/kernel/cps-vec.S: Assembler messages:
arch/mips/kernel/cps-vec.S:450: Error: operand 3 out of range `andi 
$8,$8,((1)<<25)'
So I fell back to letting the assembler generate the LUI and AND.
> For both in the series:
>
>      Reviewed-by: Paul Burton <paul.burton@xxxxxxxxxx>
Thanks Paul,
Matt

> Thanks,
>      Paul
>
> > +	beqz	t0, 3f
> > +	 nop
> > +	mfc0    t0, CP0_SEGCTL0
> > +	mttc0	t0, CP0_SEGCTL0
> > +	mfc0    t0, CP0_SEGCTL1
> > +	mttc0	t0, CP0_SEGCTL1
> > +	mfc0    t0, CP0_SEGCTL2
> > +	mttc0	t0, CP0_SEGCTL2
> > +3:
> >   	/* Ensure no software interrupts are pending */
> >   	mttc0	zero, CP0_CAUSE
> >   	mttc0	zero, CP0_STATUS
> > --
> > 2.5.0