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Re: [Xen-devel] [PATCH v2 00/41] Add ACPI support for arm64 on Xen

Hi Parth,

Thank you for the patch series.

On 17/05/2015 21:03, Parth Dixit wrote:
This patch series adds ACPI support for arm64.
Xen reads static tables described by ACPI standard (5.1) from uefi
and configures timer, gic and uart. ACPI tables are modified to
enable PSCI, HVC and xen specific information (grant table and
event channel interrupts) and mapped into dom0 address space.
A skeleton device tree is created to pass efi table which contains
memory layout (which cannot be passed using ACPI) and rsdp pointer to DOM0.
DOM0 parses dynamic ACPI tables and configure other peripherals.

Patches 1-21 add ACPI support for xen/uefi interface
Patches 22-41 add ACPI support for xen/Dom0 interface
Last patch "xen: arm64: Add ACPI support" enables the support for ACPI
so that individual patches do not affect working xen code base.

Patches are tested on FVP base model and same binary is working for ACPI as 
well as
device tree.(32 bit is not tested).

I will give a try on 32 bits when I will review the patches.

ACPI is now configurable via commandline option "acpi".
To boot from ACPI this parameter should be set to "force".

Wouldn't it be possible to detect automatically if we need to use ACPI or not? IIRC it's what Linux does.

Instructions for reproducing the setup and working code base can be found
in the following repositories
wiki : https://wiki.linaro.org/LEG/Engineering/Xen_boot_on_FVP_ACPI_UEFI
linux : https://git.linaro.org/people/parth.dixit/xen-upstreaming/leg-kernel.git

Linux 4.1 has ACPI support for ARM64. What are the missing parts in order to use upstream Linux as DOM0? What's the plan to upstream them?

Few workarounds have been made to get it working, these are as follows
1. In Xen interrupts are routed at the boot time with edge/trigger level set to 0
because this information is not available at the time of booting.

edge/trigger is only a bit. Can't you just avoid to set it rather than using a potentially incorrect value?

2. EFI runtime services are disaled in linux but proper solution has to come 
from linux side.

Can you details a bit more? What is missing?


Julien Grall

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