Re: Arndale secondary CPU boot issue Was Re: [xen-unstable test] 60076: regressions - FAIL

[Julien Grall <julien.grall@citrix.com>]

Hi Ian,

On 30/07/15 09:55, Ian Campbell wrote:
> On Wed, 2015-07-29 at 19:18 +0100, Julien Grall wrote:
>> It appears to be required on the Arndale to boot secondaries CPUs.
>> Although, depending on where I put the sev I don't have the same 
>> behavior:
>> 	- sev in smp_init callback: the CPU is not coming up
>> 	- sev before or after arch_cpu_up: the CPU is booting but not in 
>> HYP
>> mode [2]
>>
>> I haven't yet figured out where the "sev" should be placed in order to
>> get the CPU boot correctly.
> 
> Does the arndale end up using 
> .cpu_up = cpu_up_send_sgi,
> or
> .cpu_up = exynos5_cpu_up,
> ?

The first one given that the arndale is an exynos5250. I'm not sure why
we didn't use exynos5_cpu_up. Although it doesn't seem to fix the problem.

>> What I don't understand is how the placement of "sev" would affect the
>> secondary processor to boot in HYP mode or Kernel mode or nothing at all
>>
>> This platform seems very picky and I don't remember having a
>> documentation about how the SMP boot works for this platform. Linux
>> seems to avoid the SEV for this platform.
> 
> 32-bit Linux has some in common code paths IIRC, which are not always
> apparent at first glance.

Good to know.

Regards,

-- 
Julien Grall