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

[Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>]

On 06/21/2016 04:28 AM, Julien Grall wrote:
> 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).
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.
> 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,
--
Shanker Donthineni
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux 
Foundation Collaborative Project


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