On 12.01.2016 17:16, Marc Zyngier wrote:

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Also, the spec says:

"On systems supporting GICv3 and above, this field holds the 64-bit
physical address of the associated Redistributor. If all of the GIC
Redistributors are in the always-on power domain, GICR structures should
be used to describe the Redistributors instead, and this field must be
set to 0."

which triggers two questions:
- Can you access always the GICR_TYPER register without waking the
redistributor up?

I missed this part, can you suggest how can we do that? accessing some
register before access to redistributor?

This redistributor may be in a power-domain that is off. Are you
guaranteed that you can access GICR_TYPER even when it is off?

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- How do you cope with situations where some redistributors are in the
always-on domain, and some are not?

I'm not sure if there is such hardware, if yes, do we need to fix
the spec first?

It is something that should definitely be clarified. Can we end-up in a
situation where some redistributors are described via the GICR
structure, and some via the GICC structure? The spec is a bit ambiguous.

To recap:
1. GICR and GICC subtables should be mutually exclusive, but ACPI spec 
should be clear about this.
2. We need to know if we can access GICR_TYPER without waking the 
redistributor up.

Tirumalesh, can you please advice?

Tomasz