Re: [PATCH] QEMU - provide e820 reserve through qemu_cfg

Anthony Liguori
2010-01-25T20:14:38Z

On 01/25/2010 02:04 PM, Alexander Graf wrote:
> On 25.01.2010, at 18:46, Jes Sorensen wrote:
>
>
>> On 01/25/10 18:28, Alexander Graf wrote:
>>
>>>>> That way we'd get 2 entries and the chance to enhance them later on.
>>>>> In fact, it might even make sense to pass the whole table in such a
>>>>> form. That way qemu generates all of the e820 tables and we can
>>>>> declare whatever we want. Just add a type field in the table.
>>>>>
>>>> I am fine with having QEMU build the e820 tables completely if there is
>>>> a consensus to take that path.
>>>>
>>> I agree. We better get this right :-). I don't want to maintain 5
>>> versions of an 380 fw_cfg interface.
>>>
>> Looking at the internals, some of the e820 entries are based on compile
>> time constants for the BIOS, so it will be hard to pass those from
>> QEMU, but we could do it in a way so we pass a number of additional
>> e820 entries. Ie. address, length, and type.
>>
> Yes, sounds good. Should be fairly extensible then. What about memory holes? Do we need to take care of them?
>

It would be nice for QEMU to be able to add additional e820 regions that
don't necessarily fit the standard layout model.

For instance, I've thought a number of times about using a large
reserved region as a shared memory mechanism.

But we certainly need to allow the BIOS to define the regions it needs
to know about.

Regards,

Anthony Liguori