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Re: [Xen-devel] [PATCH 0/4] ARM: add PSCI host support

On 11/26/2013 12:05 PM, Ian Campbell wrote:
On Mon, 2013-11-25 at 13:02 +0100, Andre Przywara wrote:
Xen did not make use of the host provided ARM PSCI (Power State
Coordination Interface) functionality so far, but relied on platform
specific SMP bringup functions.
This series adds support for PSCI on the host by reading the required
information from the DTB and invoking the appropriate handler when
bringing up each single CPU.
Since PSCI is defined for both ARM32 and ARM64, I put the code in a
file shared by both.
The ARM32 code was tested on Midway, but the ARM64 code was compile
tested only.

This approach seems to be the least intrusive, but one could also use
more of the current ARM64 code by copying the PSCI/spin-table
distinction code to a shared file and use that from both
architectures. However that seems more complicated.


thanks for the review and for the willingness to take the patches for 4.4 still. Will address the comments ASAP.

I don't think that is needed (since armv7 spintable vs armv8 spintable
mechanisms are a bit different). But I would like to see the psci code
in a separate psci.c. It's not much code right now but it will likely

But there is already a xen/arch/arm/psci.c file, which holds the two functions to bring up/take down vCPUs. Not much in here, I could easily add my code there, but the scope of those two is quite different and I would find it strange to have both host and guest PSCI functions in one file. That was one reason to not create a new file, the other was that I found smpboot.c an obvious place to keep functions for SMP bringup in.

So should I use psci_host.c? Or keep it in smpboot.c (at least for the time being)?

And beside that there is quite some other (only guest related) code in Xen which simply uses *psci* in identifiers and filenames (like asm/psci.h), that's why I used the psci_host prefix to tell them apart.


I'll comment a bit more on the individual patches shortly.



Please take a look and complain ;-)

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>

Andre Przywara (4):
   arm: parse PSCI node from the host device-tree
   arm: add a function to invoke the PSCI handler and use it
   arm: dont give up on EAGAIN if PSCI is defined
   arm64: defer CPU initialization on ARM64 if PSCI is present

  xen/arch/arm/arm32/smpboot.c |  1 -
  xen/arch/arm/arm64/smpboot.c |  7 +++-
  xen/arch/arm/smpboot.c       | 89 +++++++++++++++++++++++++++++++++++++++++---
  3 files changed, 88 insertions(+), 9 deletions(-)

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