Re: [Xen-devel] [PATCH 5/6] docs: Document start_info changes in Xen 4.2.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.03.13 at 12:11, Keir Fraser <keir@xxxxxxx> wrote:
> On 18/03/2013 10:55, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>>>>> On 15.03.13 at 20:51, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
>>>>> wrote:
>>> The  25833:bb85bbccb1c9. "x86/32-on-64: adjust Dom0 initial page table
>>> layout"
>>> fixes a bug in the reported value of pt_base versus where the page tables
>>> actually start. This documents this in the start of the world header note.
>>> 
>>> This clarifies the implied understanding that the page table space is
>>> pointed by pt_base. As in it is ".. implied that the range of page-tables
>>> is the range [pt_base, pt_base + nr_pt_frames), whereas that that range
>>> here indeed is [pt_base - 2, pt_base -2 + nr_pt_frames)" (Jan Beulich).
>>> 
>>> Also make it crystal clear that pt_base == %cr3.
>> 
>> Question is - do we really want this? While I provided aforementioned
>> fix, I was never really convinced whether it was the hypervisor or
>> the kernel that misbehaved here. It just was so that dealing with this
>> on the hypervisor side was much easier.
>> 
>> Perhaps Keir would remember what the original intentions (if any)
>> were regarding the page table layout (i.e. whether the above
>> equality was really intended).
> 
> I think I did intend pt_base == cr3 == first page-table page in the
> consecutive sequence of reserved pages on domain startup.

In that case, Konrad, feel free to put my ack on that patch.

Jan


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