Re: [Xen-devel] [PATCH v2 2/2] libxl: Fix nographic with upstream qemu

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Wednesday, December 18, 2013, 8:54:39 PM, you wrote:

> 2013/12/18 Sander Eikelenboom <linux@xxxxxxxxxxxxxx>

>> Hello Sander,
>>
>> Tuesday, November 26, 2013, 1:30:41 PM, you wrote:
>>
>>
>> > Tuesday, November 26, 2013, 12:53:09 PM, you wrote:
>>
>> >> On Mon, Nov 25, 2013 at 08:39:22PM +0100, Sander Eikelenboom wrote:
>> >>>
>> >>> Monday, November 25, 2013, 8:28:27 PM, you wrote:
>> >>>
>> >>> > 2013/11/25 Anthony PERARD <anthony.perard@xxxxxxxxxx>
>> >>>
>> >>> >> On Tue, Nov 19, 2013 at 03:57:09PM +0100, Fabio Fantoni wrote:
>> >>> >> > Fix xl nographic parameter with upstream qemu using vga none
>> >>> >> > instead of -nographic qemu parameter not working anymore and
>> >>> >> > deprecated.
>> >>> >> >
>> >>> >> > Changes from v1:
>> >>> >> > - libxl_create.c:
>> >>> >> >  - add vga=none if nographic=1 only with upstream qemu
>> >>> >> >  - move setdefault of nographic up, otherwise xl create will
>> >>> >> >    fail if nographic xl paramter is not set
>> >>> >>
>> >>> >> Could you tell me where it is said that -nographic is deprecated?
>> >>> >>
>> >>>
>> >>> > On one old qemu-devel post if I remember good, I not found it now
>> with fast
>> >>> > search.
>> >>>
>> >>> this one of mine:
>> >>> http://osdir.com/ml/xen-development/2013-10/msg00134.html
>> >>>
>> >>> which refers to a post on qemu-devel:
>> >>> http://comments.gmane.org/gmane.comp.emulators.qemu/172385
>>
>> >> Thanks for the pointers.
>>
>> >>> >>
>> >>> >> Also, I've did few tests, and it look like nographic=1 still works
>> well.
>> >>> >>
>> >>>
>> >>> > When I did a tests time ago with upstream qemu gave always cirrus
>> vga with
>> >>> > hvm domUs, also with vga and stdvga not setted and nographic on.
>> >>> > Tried also removing my patches about -nodefaults but same result.
>> >>> > When I did this patches I found that xl setted cirrus in any case
>> and also
>> >>> > with -nographic with upstream qemu not override -vga or -device.
>> >>>
>> >>>
>> >>> >>
>> >>> >> In QEMU, "-vga none" and "-nographic" are two different things. The
>> >>> >> first parameter disable the graphic emulation, which mean you can
>> have a
>> >>> >> guest without graphic card (lspci will show that). The second one
>> is to
>> >>> >> disable any graphic output (sdl, vnc, ...).
>> >>> >>
>> >>> >> The only issue might be the documentation.
>> >>> >>
>> >>>
>> >>> > Sorry, about qemu traditional I haven't well documented, but on this
>> patch
>> >>> > I setted nographic equivalent to vga none only with upstream qemu,
>> so the
>> >>> > qemu-trad remain correctly.
>> >>> > Another note, I use spice with upstream qemu instead of vnc (because
>> is
>> >>> > largely better), probably -nographic not disable it.
>> >>>
>> >>> > Sumarizing, previous patch about vga none after new version
>> following your
>> >>> > advice can be useful in any case.
>> >>> > About nographic instead I am doubtful about how to proceed, I think,
>> >>> > however that an improvements and/or more documentations are needed.
>> >>> > Ideas or tips about nographic?
>>
>>
>> >> After reading those threads about nographic deprecation, it is said that
>> >> it is better to use '-display none' instead of '-nographic'.
>> >> So '-display none' just mean you get no VNC, no SDL window, no SPICE,
>> >> nothing, but you can still get a graphic card in the guest, with no way
>> >> to display its output.
>>
>> >> I suppose 'nographic' xl options should keep the same effect which is no
>> >> graphic output. So if you want a guest without graphic card, then your
>> >> new 'vga=none' will be for you.
>>
>> > Wouldn't it be more natural to do just
>> > vnc=0
>> > sdl=0
>> > vga=none
>>
>> > if i want no graphics?
>>
>> > Instead of making a "meta-option" which overrules other available
>> options ?
>> > Would simplify the parsing for libxl as well.
>>
>> Hi Anthony / Fabio,
>>
>> Just a little *ping* here ..
>> I haven't seen a response any more, nor seem Fabio's patches to be applied.
>>

> The first patch with v3 should be good:
> http://lists.xen.org/archives/html/xen-devel/2013-12/msg00725.html
> and vga none can be useful in some cases but probably will be applied only
> with xen 4.5 because 4.4 is on freeze and near to first rc.

Yes i have added it to my private patch queue now, thx :-)

> About the second patch after Anthony reply I understand that the patch is
> bad, I do not know how to improve this part in the best way and I'm
> currently busy with many other things.

Yes but i wasn't convinced and haven't seen a response from Anthony to that.

Because having such a meta-option that effects the behaviour of a set of 
individual options
seems to make the problem of precedence appear which is ambiguous.

f.e. if I specifying vnc=1 and nographic=1 .. should vnc be on or off now, so 
which option
should take precedence over the other ?

So i don't see the real benefit of a meta-option above just switching the 
individual components on or off.
If you want them all off .. then just specify that.

The less ambiguous the better i would say.


>>
>> --
>> Sander
>>
>> > --
>> > Sander
>>
>>
>>
>> --
>> Best regards,
>>  Sander                            mailto:linux@xxxxxxxxxxxxxx
>>
>>


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