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





On 21/06/16 15:16, Shanker Donthineni wrote:
On 06/21/2016 08:50 AM, Julien Grall wrote:
On 21/06/16 14:37, Shanker Donthineni wrote:
On 06/21/2016 04:28 AM, Julien Grall wrote:
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).

I agree with you, we need to bring binary search algorithm similar to
Linux KVM code. I want to keep it this change outside of this patchset.

This should be a prerequisite of this series then, not a follow-up.

For the  functionality and correctness purpose we don't need this change
immediately.
We are not able to boot XEN on Qualcomm Technologies because of not
supporting
GICC table parsing for GICR address.

I am okay to wait for my patchset if someone adding bseach look ups for
mmio handlers.

I am not aware of anyone planning to add bsearch.

Regards,

--
Julien Grall

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