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

[Julien Grall <julien.grall@citrix.com>]

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?

Regards,

-- 
Julien Grall