Re: [Qemu-devel] [PATCH RFC] spapr: by-pass SLOF when -kernel is provided

[Alexey Kardashevskiy]

On 06/07/16 11:35, David Gibson wrote:
> On Tue, Jul 05, 2016 at 04:42:37PM +0200, Laurent Vivier wrote:
>> As device-tree is now fully built by QEMU, we don't need SLOF
>> anymore if the kernel is provided on the command line.
>>
>> In this case, don't load SLOF and boot directly into the
>> kernel.
>>
>> This saves at least 5 seconds on the boot sequence.
>>
>> Signed-off-by: Laurent Vivier <address@hidden>
> 
> I'm not comfortable applying this.  We actually used to do this ages
> ago, but changed to always running through SLOF, and there were
> reasons for doing so.
> 
> I don't remember exactly what they were, but I think it boiled down to
> slight differences in state between booting from SLOF and booting
> without SLOF leading to confusing errors from the guest kernel.
> 

PCI resource allocation is still done by SLOF (however having them not set
will trigger allocation in the guest but this is rather unexpected
workaround than a feature); "client-architecture-support" won't work
without SLOF either (i.e. compatibile PowerISA 2.0x CPUs).



-- 
Alexey

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