Re: [PATCH RESEND 00/14] Xen ARM DomU ACPI support

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2016/6/6 23:48, Julien Grall wrote:
> Hi Wei,
> 
> On 06/06/16 13:26, Wei Liu wrote:
>> On Tue, May 31, 2016 at 01:02:52PM +0800, Shannon Zhao wrote:
>>> From: Shannon Zhao <shannon.zhao@linaro.org>
>>>
>>> The design of this feature is described as below.
>>> Firstly, the toolstack (libxl) generates the ACPI tables according the
>>> number of vcpus and gic controller.
>>>
>>> Then, it copies these ACPI tables to DomU memory space and passes
>>> them to UEFI firmware through the "ARM multiboot" protocol.
>>>
>>> At last, UEFI gets the ACPI tables through the "ARM multiboot" protocol
>>> and installs these tables like the usual way and passes both ACPI and DT
>>> information to the Xen DomU.
>>>
>>> Currently libxl only generates RSDP, XSDT, GTDT, MADT, FADT, DSDT tables
>>> since it's enough now.
>>>
>>> This has been tested using guest kernel with the Dom0 ACPI support
>>> patches which could be fetched from:
>>> https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/log/?h=efi/arm-xen
>>>
>>>
>>> Shannon Zhao (14):
>>>    libxl/arm: Fix the function name in error log
>>>    libxl/arm: Factor out codes for generating DTB
>>>    libxc: Add placeholders for ACPI tables blob and size
>>>    tools: add ACPI tables relevant definitions
>>>    libxl/arm: Construct ACPI GTDT table
>>>    libxl/arm: Construct ACPI FADT table
>>>    libxl/arm: Construct ACPI DSDT table
>>>    libxl/arm: Construct ACPI MADT table
>>>    libxl/arm: Construct ACPI XSDT table
>>>    libxl/arm: Construct ACPI RSDP table
>>>    libxl/arm: Initialize domain param HVM_PARAM_CALLBACK_IRQ
>>>    libxl/arm: Add ACPI module
>>>    libxl/arm: initialize memory information of ACPI blob
>>>    libxc/xc_dom_core: Copy ACPI tables to guest memory space
>>>
>>
>> After going through this series, I think the code mostly looks good.
>>
>> There is one higher level question: you seem to have put a lot of the
>> table construction code in libxl, while I failed to see why specific
>> libxl information is needed. Have you considered moving the code to
>> libxc?
> 
> I would rather avoid to have the device tree built by libxl and ACPI
> tables built by libxc.
> 
> I don't remember why we have decided to implement DT building in libxl,
> I guess it is because we need to know which GIC version is used (GICv2
> vs GICv3).
> 
> In the long run, we might also need to have more part of the firmware
> configurable (performance monitor support, memory layout, UART...).
> 
> Most of those information are available easily in libxl, we would to
> export them of libxc.
Yes, and one more reason is that to support ACPI, it also needs to add
the ACPI multiboot module in DT.

Thanks,
-- 
Shannon


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