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Re: [Xen-devel] [PATCH] xen/arm: Fix smp_send_call_function_mask() for current CPU



On 14/08/14 13:44, Julien Grall wrote:
On 08/14/2014 12:47 PM, Anup Patel wrote:
The smp_send_call_function_mask() does not work on Foundation v8
model with one CPU. The reason being gicv2_send_SGI() is called
with irqmode==SGI_TARGET_LIST and *cpu_mask=0x1 on CPU0 which
does not work on Foundation v8 model.

Please provide any steps, trace that make you think that irqmode ==
SGI_TARGET_LIST and *cpu_mask=0x1 is not working on Foundation V8 Model.

Further, it is really strange that smp_send_call_function_mask()
depends on GIC SGIs for calling function on current CPU.

Why it's strange??? The GIC specification doesn't seem to add any
restriction about sending an SGI to the current CPU.

It clearly looks like a bug in another part of Xen. And I doubt it's
because the Foundation Model is not able to support the use case above.

Without any further explanation than "It doesn't work" and "It's
strange", I don't think this patch should be accepted in Xen.
You need at least to point the paragraph in the spec...

This patch fixes smp_send_call_function_mask() for current CPU
by directly calling smp_call_function_interrupt() on current CPU.
This is very similar to what Xen x86 does.

What was done in x86 may not make sense on ARM....

For me the current code is valid... So far, I didn't see any issue on
different boards. I've also used recently the Foundation v8 Model [1],
without any issue.

I just saw their is new version of the model. I've tested sucessfully xen on:

ARM V8 Foundation Model r0p0 (model build 0.8.5206)

I will give a try on newer version.

Regards,

--
Julien Grall

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