[PATCH 01/16] ARM: b.L: secondary kernel entry code

[Santosh Shilimkar]

On Friday 11 January 2013 11:40 PM, Nicolas Pitre wrote:
> On Fri, 11 Jan 2013, Santosh Shilimkar wrote:
>
>> On Thursday 10 January 2013 05:50 AM, Nicolas Pitre wrote:
>>> +ENTRY(bL_entry_point)
>>> +
>>> + THUMB(	adr	r12, BSYM(1f)	)
>>> + THUMB(	bx	r12		)
>>> + THUMB(	.thumb			)
>>> +1:
>>> +	mrc	p15, 0, r0, c0, c0, 5
>>> +	ubfx	r9, r0, #0, #4			@ r9 = cpu
>>> +	ubfx	r10, r0, #8, #4			@ r10 = cluster
>>> +	mov	r3, #BL_CPUS_PER_CLUSTER
>>> +	mla	r4, r3, r10, r9			@ r4 = canonical CPU index
>>> +	cmp	r4, #(BL_CPUS_PER_CLUSTER * BL_NR_CLUSTERS)
>>> +	blo	2f
>>> +
>>> +	/* We didn't expect this CPU.  Try to make it quiet. */
>>> +1:	wfi
>>> +	wfe
>>
>> Why do you need a wfe followed by wif ?
>> Just curious.
>
> If the WFI doesn't work because an interrupt is pending then the WFE
> might work better.  But as I mentioned before, this is not intended to
> be used for other purposes than "we're really screwed so at least let's
> try to cheaply quieten this CPU" case.
>
Thanks for clarification.

Regards
Santosh