[U-Boot] [PATCH] MIPS: Hang if run on a secondary CPU

[Paul Burton]

On Wednesday, 21 September 2016 12:59:39 BST Langer, Thomas wrote:
> Hello Paul,
> 
> > diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
> > index fc6dd66..dd37ac3 100644
> > --- a/arch/mips/cpu/start.S
> > +++ b/arch/mips/cpu/start.S
> > @@ -112,6 +112,31 @@ ENTRY(_start)
> > 
> >  	.align 4
> >  
> >  reset:
> > +#if __mips_isa_rev >= 6
> > +	.set	push
> > +	.set	reorder
> > +	mfc0	t0, CP0_CONFIG, 1
> > +	bgez	t0, 1f
> > +	mfc0	t0, CP0_CONFIG, 2
> > +	bgez	t0, 1f
> > +	mfc0	t0, CP0_CONFIG, 3
> > +	bgez	t0, 1f
> > +	mfc0	t0, CP0_CONFIG, 4
> > +	bgez	t0, 1f
> > +	mfc0	t0, CP0_CONFIG, 5
> > +	and	t0, t0, MIPS_CONF5_VP
> > +	beqz	t0, 1f
> > +
> > +	mfc0	t0, CP0_GLOBALNUMBER
> > +	b	2f
> > +	.set	pop
> > +#endif
> > +
> > +1:	mfc0	t0, CP0_EBASE
> > +	and	t0, t0, EBASE_CPUNUM
> > +
> > +	/* Hang if this isn't the first CPU in the system */
> > +2:	bnez	t0, .
> 
> This loop should include a "wait" instruction.
> Otherwise the CPU will burn power for doing nothing.
> 
> Thomas

Hi Thomas,

True, it would spin until (typically) it gets reset by Linux or whatever OS is 
booted. I'll add a wait.

Thanks,
    Paul