Re: [Xen-devel] [PATCH v2] docs: add PVH specification

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.09.14 at 18:03, <david.vrabel@xxxxxxxxxx> wrote:
> On 18/09/14 16:57, Jan Beulich wrote:
>>>>> On 18.09.14 at 17:27, <roger.pau@xxxxxxxxxx> wrote:
>>> +All the segments selectors are set with a flat base at zero.
>>> +
>>> +The `cs` segment selector attributes are set to 0x0a09b, which describes an
>>> +executable and readable code segment only accessible by the most privileged
>>> +level. The segment is also set as a 64-bit code segment (`L` flag set) 
>>> with 
> a
>>> +default operation size of 16bits (`D` flag unset).
>> 
>> There's no such thing - the L bit set requires the D bit to be clear
>> _without_ this meaning a default operation size of 16 bits.
>> 
>>> +The remaining segment selectors (`ds`, `ss`, `es`, `fs` and `gs`) are all 
> set
>>> +to the same values. The attributes are set to 0x0c093, which implies a 
>>> read 
> and
>>> +write data segment only accessible by the most privileged level. It is 
> important
>>> +to notice that for the `ss` selector the stack is set to use a 32bit 
> pointer
>>> +(`B` flag set).
>> 
>> The B bit really has no meaning in 64-bit mode, and the stack pointer
>> will always be a 64-bit one.
> 
> Perhaps this doc should avoid explaining what the bits mean?  The Intel
> or AMD reference manuals can be used for this.

Perhaps, but in that case specifying the attributes as raw hex
number is probably sub-optimal.

Jan


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