Re: [PATCH V3 1/1] libxl: set stub domain size based on VRAM size

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2015-07-15 at 10:45 +0100, Ian Campbell wrote:
> On Sat, 2015-07-11 at 17:30 -0400, Eric Shelton wrote:
> > Allocate additional memory to the stub domain for qemu-traditional if
> > more than 4 MB is assigned to the video adapter to avoid out of memory
> > condition for QEMU.
> 
> In reply to v2 (after you'd sent v3, I think) Ian J said:
> > Well, it does also reduce the stubdom memory when the video memory is
> > <4Mby.  That sounds plausible to me but at the very least the commit
> > message needs changing, and maybe we should wait a bit to see if one
> > of the qemu experts objects.
> 
> libxl__domain_build_info_setdefault ensures, for qemu-xen-traditional,
> that video_memkb is either precisely 4M (TYPE_CIRRUS) or >= 8M
> (TYPE_STD) but allows a free choice for TYPE_NONE, defaulting to 0 (I'd
> almost expect it to insist on 0, but there you are).
> 
> I suggest adding a second paragraph to the commit message:
> 
>         For LIBXL_VGA_INTERFACE_TYPE_STD + CIRRUS video_memkb is always
>         at least 4MB. However if LIBXL_VGA_INTERFACE_TYPE_STD is
>         selected the video_memkb defaults to 0, resulting in a stubdom
>         which is 4MB smaller than before. It seems unlikely that VGA
>         disable would require more memory then the other options, so
>         this should be ok.
> 
> I'm happy to add that while I commit and will Ack + do so tomorrow
> unless somebody objects during today.

Done.