Re: [PATCH 0/8] x86, acpi: Move acpi_initrd_override() earlier.

Zhang Yanfei
2013-08-23T17:30:33Z

Hi Toshi,

On 08/24/2013 01:13 AM, Toshi Kani wrote:
> Hello,
>
> On Fri, 2013-08-23 at 12:24 -0400, Tejun Heo wrote:
>> On Fri, Aug 23, 2013 at 10:14:08AM -0600, Toshi Kani wrote:
>>> I still think acpi table info should be available earlier, but I do not
>>> think I can convince you on this. This can be religious debate.
>>
>> I'm curious. If there aren't substantial enough benefits, why would
>> you still want to pull it earlier when it brings in things like initrd
>> override and crafting the code carefully so that it's safe to execute
>> it from different address modes and so on? Please note that x86 is
>> not ia64. The early environment is completely different not only
>> technically but also in its diversity and suckiness. It wasn't too
>> long ago that vendors were screwing up ACPI left and right. It has
>> been getting better but there's a reason why, for example, we still
>> consider e820 to be the authoritative information over ACPI.
>
> Firmware generates tables, and provides them via some interface. Memory
> map table can be provided via e820 or EFI memory map. Memory topology
> table is provided via ACPI. I agree to prioritize one table over the
> other when there is overlap. But in the end, it is the firmware that
> generates the tables. Because it is provided via ACPI does not make it
> suddenly unreliable. I think table info from e820/EFI/ACPI should be
> available at the same time. To me, it makes more sense to use the
> hotplug info to initialize memblock than try to find a way to workaround
> without it.

Yeah, agreed. But sigh.... on x86, we have ACPI initrd override, so we still
cannot convince Tj....

I think we will continue to be in that way to find a
> workaround in this direction.
>
> I came from ia64 background, and am not very familiar with x86. So, you
> may be very right about that x86 is different. I also agree that initrd
> is making it unnecessarily complicated. We may see some initial issues,
> but my hope is that the code gets matured over the time.
>
> Thanks,
> -Toshi
>

--
Thanks.
Zhang Yanfei