Re: 2.6.25-rc1 xen pvops regression

H. Peter Anvin
2008-02-22T16:32:44Z

Andi Kleen wrote:
> Alan Cox wrote:
>>> Actually I switched 64bit over to trust e820 completely and not
>>> reserve 640k-1MB explicitly some time ago
>>> and AFAIK there hasn't been any reports that it causes problems.
>>>
>>> So presumably trusting e802 is ok on modern systems (2003+)
>> Apparently so - at least 64bit capable ones.
>
> They should all use the same BIOS code bases, except perhaps
> some embedded weirdnesses.

Well, that, plus you still have to deal with a lot older stuff.

> We do still sort the entries
>> to remove zero length records and other suprises.
>
> That code could be actually dropped. And the sorting too.
> It's all not needed I think.

When I dealt with this for another project, I found that the e820 data
format is suboptimal. It's better to treat it as a sorted list of
(address, type) tuples (where type can be zero); the data from e820 can
be fed into such a data structure and it cleans it up nicely.

-hpa