Re: [Xen-devel] [PATCH v4 4/5] x86: add multiboot2 protocol support for EFI platforms

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.01.17 at 12:37, <daniel.kiper@xxxxxxxxxx> wrote:
> On Thu, Jan 19, 2017 at 02:09:37AM -0700, Jan Beulich wrote:
>> >>> On 18.01.17 at 20:51, <andrew.cooper3@xxxxxxxxxx> wrote:
>> > Are we strictly guaranteed to have the entire image, including multiboot
>> > tags, loaded below 4GB virtual even in the 64bit case? Even on non-EFI
>> > capable grub2's ?
>>
>> I can't speak for GrUB, but I've recently learned that EFI alone
>> doesn't appear to make such guarantees, and also doesn't look
>> to have ways to request such address restricted loading of an
> 
> Why? Due to lack of memory below 4 GiB, it being reserved for
> something, EFI implementation bugs or anything else?

I don't know the precise reason in that specific case, but I did go
through the spec again after I had read that report, and I wasn't
able to find anything regarding mandated or optional address
restrictions. My recollection of there being such a restriction must
have been based on the EFI sample implementation and/or the
EDK.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel