Re: [RFC] [PATCH 10/16] x86_64: 64bit PIC ACPI wakeup

[ebiederm@xmission.com (Eric W. Biederman)]

Pavel Machek <pavel@suse.cz> writes:

> Hi!
>
>> - Killed lots of dead code
>> - Improve the cpu sanity checks to verify long mode
>>   is enabled when we wake up.
>> - Removed the need for modifying any existing kernel page table.
>> - Moved wakeup_level4_pgt into the wakeup routine so we can
>>   run the kernel above 4G.
>> - Increased the size of the wakeup routine to 8K.
>> - Renamed the variables to use the 64bit register names.
>> - Lots of misc cleanups to match trampoline.S
>> 
>> I don't have a configuration I can test this but it compiles cleanly
>
> Ugh, now that's a big patch.. and untested, too :-(.

It was very carefully code reviewed at least the first time,
and the code was put in sync with code that was tested.

But things happens so the lack of testing was noted.

> Why is PGE no longer required, for example?

PGE is never required.  Especially on a temporary page table.
PGE is an optimization, to make context switches faster.

> Can we get it piece-by-piece?


>> Vivek has tested this patch for suspend to memory and it works fine.
>
> Ok, so it was tested on one config. Given that the patch deals with
> detecting CPU oddities... :-(

Read the code.  Given your scorn and the state of that mess when I
started I'm not certain a productive conversation can be had.

Do you understand the code as it is currently written?

Eric