2014-05-02 21:44 GMT+02:00 Don Slutz <= ;dslutz@verizon.com= >:

<= blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-l= eft:1px solid rgb(204,204,204);padding-left:1ex">

On 05/02/14 07:41, Ian Campbell wrote:

On Sat, 2014-04-19 at 14:16 +0200, Fabio Fantoni wrote:

Reading one qemu-devel post seems that setting video memory of
cirrus vga with upstream qemu is wrong even if not show errors.

Fabio,
=C2=A0 You can add my:

Reviewed-by: Don Slutz <dslutz@verizon.com>

I have a similar code change locally (part of my pending
list of to dos) (I just changed the global arg...).

You later provided links but I think the conversation should be
referenced here.

I was part of the conversation. =C2=A0When I was looking into upstreaming a change I have (pci_min_hole) to xen & qemu, I was asked by QEMU
to report if it was not used (i.e. non x86 cpu's). =C2=A0While I was te= sting my
change to QEMU under xen I noticed:

Warning: "-global vga.vram_size_mb=3D16" not used

In /var/log/xen/qemu-dm-<guest>.log

Here is the cross post to xen-devel:

=C2=A0[Xen-devel] [PATCH v3 2/4] GlobalProperty: Display warning about unus= ed -global

http://lists.xen.org/archives/html/xen-devel/2= 014-03/msg03128.html

Is this change correct for all versions of mainline qemu which people
might be using with Xen?

What I know is that "-global cirrus-vga.vgamem_mb=3D32" does work=
with upstream QEMU 1.5.0, 1.6.0, 1.7.0 and 2.0.0. =C2=A0I had added a debug=
output into the QEMU version above that show the amount of video ram
that gets allocated and so the testing was quick and easy. =C2=A0My
understanding of QEMU is that when specified this way:

=C2=A0"-device cirrus-vga,vgamem_mb=3D32"

the error checking in QEMU will report when it does not like it:

qemu-system-x86_64: Property '.vram_size_mb' not found

(unlike -global). =C2=A0So while I have not tested it, I would guess that any QEMU that accepts "-device cirrus-vga" will also either
accept the change or report and error and not start. (Note: the
change from "-vga cirrus" to "-device cirrus-vga" was d= one since
4.3.0 and has yet to generate a bug).

Thank= s for your reply, probably with my bad english I not understand good this p= art of your reply.

I changed to -device following this offici= al qemu doc:
http://git.qemu.org/?p=3Dqemu.git;a=3Dblob_plain= ;f=3Ddocs/qdev-device-use.txt;hb=3Dmaster
I did several= tests of additional vga= 9;s parameters without using the -global = in recent days with cirrus<= /span>, stdvga and qxl, I've ne= ver seen errors and the amo= unt of videoram by <= span class=3D"">domUs seem = ok.

=C2=A0

Please can you also explain what "wrong" means? Does it crash? Do= es it
silently ignore the setting? Does it do something else "wrong"? H= ow bad
is it?

For me it just silently ignores the setting. =C2=A0Which means that the
cirrus vga has the default memory and so will not support any
display setting that needs more memory (the most likely reason
videoram=3D32 is specified in the config file).

I feel it is bad enough that a backport to 4.4 makes sense to
me.

Hope this helps.
=C2=A0 =C2=A0 -Don Slutz

Signed-off-by: Fabio Fantoni <fabio.fantoni@m2r.biz>

---

Note:
- when this patch will be accepted upstream should be
=C2=A0 =C2=A0backported also on xen 4.4

I think this very much depends on what you mean by "wrong" above.=

- with this qemu parameters seems correct but for further
=C2=A0 =C2=A0confirmation I posted a question about it:
http://lists.xen.org/archives/html/xen-devel/2= 014-04/msg02606.html

Any reply to this question?

Anthony, Stefano: Opinions on this change?

---
=C2=A0 tools/libxl/libxl_dm.c | =C2=A0 =C2=A05 ++---
=C2=A0 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 8abed7b..90f19b7 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -508,9 +508,8 @@ static char ** libxl__build_device_model_args_ne= w(libxl__gc *gc,
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 flexarray_append_pair(dm_a= rgs, "-device", "VGA");
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 break;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 case LIBXL_VGA_INTERFACE_TYPE_CIR= RUS:
- =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0flexarray_append_pair(dm_args, &= quot;-device", "cirrus-vga");
- =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0flexarray_append_pair(dm_args, &= quot;-global",
- =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0GCSPRINTF("vg= a.vram_size_mb=3D%d",
+ =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0flexarray_append_pair(dm_args, &= quot;-device",
+ =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0GCSPRINTF("ci= rrus-vga,vgamem_mb=3D%d",
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 libxl__sizek= b_to_mb(b_info->video_memkb)));
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 break;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 case LIBXL_VGA_INTERFACE_TYPE_NONE:

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