Re: [Xen-devel] [PATCH 4/5] xen: fix handling framebuffer located above 4GB

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.05.19 at 17:32, <marmarek@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, May 06, 2019 at 05:15:19PM +0200, Juergen Gross wrote:
>> On 06/05/2019 16:50, Marek Marczykowski-Górecki wrote:
>> > diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
>> > index ccdffc0..b0f0f7e 100644
>> > --- a/xen/include/public/xen.h
>> > +++ b/xen/include/public/xen.h
>> > @@ -923,6 +923,8 @@ typedef struct dom0_vga_console_info {
>> >              /* Mode attributes (offset 0x0, VESA command 0x4f01). */
>> >              uint16_t mode_attrs;
>> >  #endif
>> > +            /* high 32 bits of lfb_base */
>> > +            uint32_t ext_lfb_base;
>> 
>> You will need to put this addition into an:
>> 
>> #if __XEN_INTERFACE_VERSION__ >= 0x00040d00
>> ...
>> #endif
>> 
>> section (only available from Xen 4.13 onwards).
> 
> Why exactly? I don't see this structure used in any hypercall argument.
> The only externally accessible place is start_info structure, where it
> has explicit struct size already.

In addition to Jürgen's reply: While the structure isn't meant to
be used that way, any consumer of the Xen headers could in
principle create instances of it (rather than just using pointers
to the Xen-provided instance), and without the consuming code
signaling its awareness such structure sizes may not change.

Jan


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