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Re: [Xen-devel] [PATCH 0/8] Add support for parsing per CPU Redistributor entry



Hello Shanker,

On 19/06/16 00:45, Shanker Donthineni wrote:
The current driver doesn't support parsing Redistributor entries that
are described in the MADT GICC table. Not all the GIC implementors
places the Redistributor regions in the always-on power domain. On
systems, the UEFI firmware should describe Redistributor base address
in the associated GIC CPU Interface (GICC) instead of GIC Redistributor
(GICR) table.

The maximum number of mmio handlers and struct vgic_rdist_region
that holds Redistributor addresses are allocated through a static
array with hardcoded size. I don't think this is the right approach
and is not scalable for implementing features like this. I have
decided to convert static to dynamic allocation based on comments
from the below link.

https://patchwork.kernel.org/patch/9163435/

You addressed only one part of my comment. This series increases the number of I/O handlers but the lookup is still linear (see handle_mmio in arch/arm/io.c).

After this series, the maximum number of I/O handlers is 160. So in the worst case, we have to do 160 iterations before finding an handler or concluding the I/O cannot be emulated.

Regards,

--
Julien Grall

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