Re: [PATCH 3.17-rc4 v7 0/6] arm: Implement arch_trigger_all_cpu_backtrace

[Russell King - ARM Linux]

On Tue, Nov 04, 2014 at 05:05:25PM +0000, Daniel Thompson wrote:
> This week with the help of one of my colleagues (thanks Tixy) I have
> been able to run some tests and figure out what it going on on vexpress-a9.
> 
> The summary is that on some GICv1 implementations the bit to enable
> group 1 interrupts cannot be accessed using secure memory accesses. More
> specifically the presence/absence of the EnableGrp1 bit in the secure
> version GICD_CTRL register is implementation defined.
> 
> My original patches overlooked this and as a result the existing code
> will migrate all interrupts to group but then cannot enable delivery of
> group 1 interrupts.
> 
> I'm planning to respin the code so it will automatically disable FIQ
> support when the EnableGrp1 bit is not implemented. This means
> vexpress-a9 will not benefit from FIQ support but will also not be
> harmed by it.

That's good news, and it should mean that the Versatile Express starts
booting on the nightly boot tests again.  Thanks for looking into it.

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