[PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ren, Yongjie]

[-- Attachment #1: Type: text/plain, Size: 1019 bytes --]

libxl: set stdvga=1 by default when creating a hvm guest

Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x, Ubuntu, Fedora) support VBE 2.0 or later.
So, select a standard VGA card with VBE as the default emulated graphics device.
It's also a workaround for the following bug.
http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812

Signed-off-by: Yongjie Ren <yongjie.ren@intel.com>

diff -r e08cf97e76f0 tools/libxl/libxl_create.c
--- a/tools/libxl/libxl_create.c	Mon Jun 25 13:41:32 2012 +0200
+++ b/tools/libxl/libxl_create.c	Tue Jun 26 12:41:46 2012 +0800
@@ -248,7 +248,7 @@
             if (!b_info->u.hvm.boot) return ERROR_NOMEM;
         }
 
-        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, false);
+        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, true);
         libxl_defbool_setdefault(&b_info->u.hvm.vnc.enable, true);
         if (libxl_defbool_val(b_info->u.hvm.vnc.enable)) {
             libxl_defbool_setdefault(&b_info->u.hvm.vnc.findunused, true);


[-- Attachment #2: stdvga-libxl.patch --]
[-- Type: application/octet-stream, Size: 600 bytes --]

diff -r e08cf97e76f0 tools/libxl/libxl_create.c
--- a/tools/libxl/libxl_create.c	Mon Jun 25 13:41:32 2012 +0200
+++ b/tools/libxl/libxl_create.c	Tue Jun 26 12:41:46 2012 +0800
@@ -248,7 +248,7 @@
             if (!b_info->u.hvm.boot) return ERROR_NOMEM;
         }
 
-        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, false);
+        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, true);
         libxl_defbool_setdefault(&b_info->u.hvm.vnc.enable, true);
         if (libxl_defbool_val(b_info->u.hvm.vnc.enable)) {
             libxl_defbool_setdefault(&b_info->u.hvm.vnc.findunused, true);

[-- Attachment #3: Type: text/plain, Size: 126 bytes --]

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

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ian Campbell]

On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> libxl: set stdvga=1 by default when creating a hvm guest
> 
> Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x, Ubuntu, Fedora) support VBE 2.0 or later.
> So, select a standard VGA card with VBE as the default emulated graphics device.

I'm not expert on the graphics side of HVM, but on the face of it
switching the default to something more modern seems like a reasonable
idea, although I'm not sure if we should be doing this for 4.2 at this
point.

I've CCd Tim and Stefano for input from the HVM and QEMU sides.

> It's also a workaround for the following bug.
> http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812

Do you understand the root cause of that bug?

It's hard to see how detaching a VF relates to the VGA emulation in use.
Can you explain it? Are you sure you aren't just masking the real issue
here?

> Signed-off-by: Yongjie Ren <yongjie.ren@intel.com>
> 
> diff -r e08cf97e76f0 tools/libxl/libxl_create.c
> --- a/tools/libxl/libxl_create.c	Mon Jun 25 13:41:32 2012 +0200
> +++ b/tools/libxl/libxl_create.c	Tue Jun 26 12:41:46 2012 +0800
> @@ -248,7 +248,7 @@
>              if (!b_info->u.hvm.boot) return ERROR_NOMEM;
>          }
>  
> -        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, false);
> +        libxl_defbool_setdefault(&b_info->u.hvm.stdvga, true);
>          libxl_defbool_setdefault(&b_info->u.hvm.vnc.enable, true);
>          if (libxl_defbool_val(b_info->u.hvm.vnc.enable)) {
>              libxl_defbool_setdefault(&b_info->u.hvm.vnc.findunused, true);
> 

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Stefano Stabellini]

On Tue, 26 Jun 2012, Ian Campbell wrote:
> On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > libxl: set stdvga=1 by default when creating a hvm guest
> > 
> > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x, Ubuntu, Fedora) support VBE 2.0 or later.
> > So, select a standard VGA card with VBE as the default emulated graphics device.
> 
> I'm not expert on the graphics side of HVM, but on the face of it
> switching the default to something more modern seems like a reasonable
> idea, although I'm not sure if we should be doing this for 4.2 at this
> point.
> 
> I've CCd Tim and Stefano for input from the HVM and QEMU sides.

I think it is a good thing.
The only thing to keep in mind is that QEMU upstream is switching to
16MB of videoram for stdvga. So at some point in the near future
upstream QEMU will stop working correctly with xen 4.2, unless we bump
the videoram to 16MB too.


> > It's also a workaround for the following bug.
> > http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812
> 
> Do you understand the root cause of that bug?
> 
> It's hard to see how detaching a VF relates to the VGA emulation in use.
> Can you explain it? Are you sure you aren't just masking the real issue
> here?

Indeed. We cannot possibly accept the patch on the basis that it looks
like it is masking an unrelated pci-passthrough bug.

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ren, Yongjie]

> -----Original Message-----
> From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> Sent: Wednesday, June 27, 2012 1:00 AM
> To: Ian Campbell
> Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> Stefano Stabellini
> Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> guest
> 
> On Tue, 26 Jun 2012, Ian Campbell wrote:
> > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > libxl: set stdvga=1 by default when creating a hvm guest
> > >
> > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> Ubuntu, Fedora) support VBE 2.0 or later.
> > > So, select a standard VGA card with VBE as the default emulated
> graphics device.
> >
> > I'm not expert on the graphics side of HVM, but on the face of it
> > switching the default to something more modern seems like a
> reasonable
> > idea, although I'm not sure if we should be doing this for 4.2 at this
> > point.
> >
> > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> 
> I think it is a good thing.
> The only thing to keep in mind is that QEMU upstream is switching to
> 16MB of videoram for stdvga. So at some point in the near future
> upstream QEMU will stop working correctly with xen 4.2, unless we bump
> the videoram to 16MB too.
> 
Yes, we should pay attention to this when using upstream QEMU.

> 
> > > It's also a workaround for the following bug.
> > > http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812
> >
> > Do you understand the root cause of that bug?
> >
I don't understand the root cause.

> > It's hard to see how detaching a VF relates to the VGA emulation in use.
> > Can you explain it? Are you sure you aren't just masking the real issue
> > here?
> 
It's strange that detaching a VF may break the graphics display.
As it only happens when 'stdvga=0', it might not be a normal usage.

> Indeed. We cannot possibly accept the patch on the basis that it looks
> like it is masking an unrelated pci-passthrough bug.
>
I don't want to mask that bug, either. :-)
The following sentence is quoted from xl.cfg man page.
"If your guest supports VBE 2.0 or later (e.g. Windows XP onwards) 
then you should enable this (stdvga option)."
If we set 'stdvga=1', we will not meet the bug (#1812).
I assume many Xen users (including me) are not very familiar with 'stdvga' and 
will leave it as default (it's 0 before my patch). 
If then, users may meet something *strange* like bug #1812.
I don't think it's friendly to end users, so I set the default value of 'stdvga' to '1'.

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ian Campbell]

On Wed, 2012-06-27 at 02:45 +0100, Ren, Yongjie wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > Sent: Wednesday, June 27, 2012 1:00 AM
> > To: Ian Campbell
> > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > Stefano Stabellini
> > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > guest
> > 
> > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > >
> > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > So, select a standard VGA card with VBE as the default emulated
> > graphics device.
> > >
> > > I'm not expert on the graphics side of HVM, but on the face of it
> > > switching the default to something more modern seems like a
> > reasonable
> > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > point.
> > >
> > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > 
> > I think it is a good thing.
> > The only thing to keep in mind is that QEMU upstream is switching to
> > 16MB of videoram for stdvga. So at some point in the near future
> > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > the videoram to 16MB too.
> > 
> Yes, we should pay attention to this when using upstream QEMU.
> 
> > 
> > > > It's also a workaround for the following bug.
> > > > http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812
> > >
> > > Do you understand the root cause of that bug?
> > >
> I don't understand the root cause.
> 
> > > It's hard to see how detaching a VF relates to the VGA emulation in use.
> > > Can you explain it? Are you sure you aren't just masking the real issue
> > > here?
> > 
> It's strange that detaching a VF may break the graphics display.
> As it only happens when 'stdvga=0', it might not be a normal usage.
> 
> > Indeed. We cannot possibly accept the patch on the basis that it looks
> > like it is masking an unrelated pci-passthrough bug.
> >
> I don't want to mask that bug, either. :-)
> The following sentence is quoted from xl.cfg man page.
> "If your guest supports VBE 2.0 or later (e.g. Windows XP onwards) 
> then you should enable this (stdvga option)."
> If we set 'stdvga=1', we will not meet the bug (#1812).
> I assume many Xen users (including me) are not very familiar with 'stdvga' and 
> will leave it as default (it's 0 before my patch). 
> If then, users may meet something *strange* like bug #1812.
> I don't think it's friendly to end users, so I set the default value
> of 'stdvga' to '1'.

There are good reasons which justify setting stdvga=1 by default. But
anything to do with #1812 is not one of them. It is obviously wrong to
justify making an unrelated configuration change on the basis that it
hides a bug by default without first understanding the reasons for the
bug.

I certainly hope you are not planning to close #1812 and stop
investigating it if we change the stdvga default.

Ian.

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Pasi Kärkkäinen]

On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > Sent: Wednesday, June 27, 2012 1:00 AM
> > To: Ian Campbell
> > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > Stefano Stabellini
> > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > guest
> > 
> > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > >
> > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > So, select a standard VGA card with VBE as the default emulated
> > graphics device.
> > >
> > > I'm not expert on the graphics side of HVM, but on the face of it
> > > switching the default to something more modern seems like a
> > reasonable
> > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > point.
> > >
> > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > 
> > I think it is a good thing.
> > The only thing to keep in mind is that QEMU upstream is switching to
> > 16MB of videoram for stdvga. So at some point in the near future
> > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > the videoram to 16MB too.
> > 
> Yes, we should pay attention to this when using upstream QEMU.
> 

Earlier there was a discussion about upstream QEMU lacking support
for being able to specify/configure the amount of videomem.

You can do that with the current qemu-xen-traditional. 
Should those patches be upstreamed? 

-- Pasi

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Stefano Stabellini]

[-- Attachment #1: Type: text/plain, Size: 1948 bytes --]

On Wed, 27 Jun 2012, Pasi Kärkkäinen wrote:
> On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > > -----Original Message-----
> > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > To: Ian Campbell
> > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > Stefano Stabellini
> > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > > guest
> > > 
> > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > >
> > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > So, select a standard VGA card with VBE as the default emulated
> > > graphics device.
> > > >
> > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > switching the default to something more modern seems like a
> > > reasonable
> > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > point.
> > > >
> > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > > 
> > > I think it is a good thing.
> > > The only thing to keep in mind is that QEMU upstream is switching to
> > > 16MB of videoram for stdvga. So at some point in the near future
> > > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > > the videoram to 16MB too.
> > > 
> > Yes, we should pay attention to this when using upstream QEMU.
> > 
> 
> Earlier there was a discussion about upstream QEMU lacking support
> for being able to specify/configure the amount of videomem.
> 
> You can do that with the current qemu-xen-traditional. 
> Should those patches be upstreamed? 

QEMU is getting a configurable videoram in the same patch series it is
getting 16MB by default for stdvga.

[-- Attachment #2: Type: text/plain, Size: 126 bytes --]

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

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Pasi Kärkkäinen]

On Wed, Jun 27, 2012 at 11:51:05AM +0100, Stefano Stabellini wrote:
> On Wed, 27 Jun 2012, Pasi Kärkkäinen wrote:
> > On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > > > -----Original Message-----
> > > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > > To: Ian Campbell
> > > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > > Stefano Stabellini
> > > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > > > guest
> > > > 
> > > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > > >
> > > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > > So, select a standard VGA card with VBE as the default emulated
> > > > graphics device.
> > > > >
> > > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > > switching the default to something more modern seems like a
> > > > reasonable
> > > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > > point.
> > > > >
> > > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > > > 
> > > > I think it is a good thing.
> > > > The only thing to keep in mind is that QEMU upstream is switching to
> > > > 16MB of videoram for stdvga. So at some point in the near future
> > > > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > > > the videoram to 16MB too.
> > > > 
> > > Yes, we should pay attention to this when using upstream QEMU.
> > > 
> > 
> > Earlier there was a discussion about upstream QEMU lacking support
> > for being able to specify/configure the amount of videomem.
> > 
> > You can do that with the current qemu-xen-traditional. 
> > Should those patches be upstreamed? 
> 
> QEMU is getting a configurable videoram in the same patch series it is
> getting 16MB by default for stdvga.
>

Oh, nice. That should help then?

-- Pasi

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Stefano Stabellini]

[-- Attachment #1: Type: text/plain, Size: 2501 bytes --]

On Wed, 27 Jun 2012, Pasi Kärkkäinen wrote:
> On Wed, Jun 27, 2012 at 11:51:05AM +0100, Stefano Stabellini wrote:
> > On Wed, 27 Jun 2012, Pasi Kärkkäinen wrote:
> > > On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > > > > -----Original Message-----
> > > > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > > > To: Ian Campbell
> > > > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > > > Stefano Stabellini
> > > > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > > > > guest
> > > > > 
> > > > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > > > >
> > > > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > > > So, select a standard VGA card with VBE as the default emulated
> > > > > graphics device.
> > > > > >
> > > > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > > > switching the default to something more modern seems like a
> > > > > reasonable
> > > > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > > > point.
> > > > > >
> > > > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > > > > 
> > > > > I think it is a good thing.
> > > > > The only thing to keep in mind is that QEMU upstream is switching to
> > > > > 16MB of videoram for stdvga. So at some point in the near future
> > > > > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > > > > the videoram to 16MB too.
> > > > > 
> > > > Yes, we should pay attention to this when using upstream QEMU.
> > > > 
> > > 
> > > Earlier there was a discussion about upstream QEMU lacking support
> > > for being able to specify/configure the amount of videomem.
> > > 
> > > You can do that with the current qemu-xen-traditional. 
> > > Should those patches be upstreamed? 
> > 
> > QEMU is getting a configurable videoram in the same patch series it is
> > getting 16MB by default for stdvga.
> >
> 
> Oh, nice. That should help then?

Yes, but problem of the default value still exists.
Nowadays distros expect to be able to take upstream QEMU and use it with
Xen, but if we are not careful it might break when the next QEMU release
is out (1.2.0).

[-- Attachment #2: Type: text/plain, Size: 126 bytes --]

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

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ian Campbell]

On Wed, 2012-06-27 at 11:45 +0100, Pasi Kärkkäinen wrote:
> On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > > -----Original Message-----
> > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > To: Ian Campbell
> > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > Stefano Stabellini
> > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > > guest
> > > 
> > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > >
> > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > So, select a standard VGA card with VBE as the default emulated
> > > graphics device.
> > > >
> > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > switching the default to something more modern seems like a
> > > reasonable
> > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > point.
> > > >
> > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > > 
> > > I think it is a good thing.
> > > The only thing to keep in mind is that QEMU upstream is switching to
> > > 16MB of videoram for stdvga. So at some point in the near future
> > > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > > the videoram to 16MB too.
> > > 
> > Yes, we should pay attention to this when using upstream QEMU.
> > 
> 
> Earlier there was a discussion about upstream QEMU lacking support
> for being able to specify/configure the amount of videomem.

I believe you were going to send a patch documenting this? 

> 
> You can do that with the current qemu-xen-traditional. 
> Should those patches be upstreamed? 
> 
> -- Pasi
> 



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

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Pasi Kärkkäinen]

On Wed, Jun 27, 2012 at 12:12:03PM +0100, Ian Campbell wrote:
> On Wed, 2012-06-27 at 11:45 +0100, Pasi Kärkkäinen wrote:
> > On Wed, Jun 27, 2012 at 01:45:49AM +0000, Ren, Yongjie wrote:
> > > > -----Original Message-----
> > > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > > To: Ian Campbell
> > > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > > Stefano Stabellini
> > > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> > > > guest
> > > > 
> > > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > > >
> > > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > > So, select a standard VGA card with VBE as the default emulated
> > > > graphics device.
> > > > >
> > > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > > switching the default to something more modern seems like a
> > > > reasonable
> > > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > > point.
> > > > >
> > > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > > > 
> > > > I think it is a good thing.
> > > > The only thing to keep in mind is that QEMU upstream is switching to
> > > > 16MB of videoram for stdvga. So at some point in the near future
> > > > upstream QEMU will stop working correctly with xen 4.2, unless we bump
> > > > the videoram to 16MB too.
> > > > 
> > > Yes, we should pay attention to this when using upstream QEMU.
> > > 
> > 
> > Earlier there was a discussion about upstream QEMU lacking support
> > for being able to specify/configure the amount of videomem.
> 
> I believe you were going to send a patch documenting this? 
> 

Yep, I'll do that..

-- Pasi

Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm guest

[Ren, Yongjie]

> -----Original Message-----
> From: Ian Campbell [mailto:Ian.Campbell@citrix.com]
> Sent: Wednesday, June 27, 2012 3:29 PM
> To: Ren, Yongjie
> Cc: Stefano Stabellini; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org)
> Subject: RE: [PATCH 1/2] libxl: set stdvga=1 by default when creating a hvm
> guest
> 
> On Wed, 2012-06-27 at 02:45 +0100, Ren, Yongjie wrote:
> > > -----Original Message-----
> > > From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> > > Sent: Wednesday, June 27, 2012 1:00 AM
> > > To: Ian Campbell
> > > Cc: Ren, Yongjie; xen-devel@lists.xen.org; Ian Jackson; Tim (Xen.org);
> > > Stefano Stabellini
> > > Subject: Re: [PATCH 1/2] libxl: set stdvga=1 by default when creating a
> hvm
> > > guest
> > >
> > > On Tue, 26 Jun 2012, Ian Campbell wrote:
> > > > On Tue, 2012-06-26 at 07:02 +0100, Ren, Yongjie wrote:
> > > > > libxl: set stdvga=1 by default when creating a hvm guest
> > > > >
> > > > > Most of the modern OSes (e.g. Windows XP, Windows 7, RHEL6.x,
> > > Ubuntu, Fedora) support VBE 2.0 or later.
> > > > > So, select a standard VGA card with VBE as the default emulated
> > > graphics device.
> > > >
> > > > I'm not expert on the graphics side of HVM, but on the face of it
> > > > switching the default to something more modern seems like a
> > > reasonable
> > > > idea, although I'm not sure if we should be doing this for 4.2 at this
> > > > point.
> > > >
> > > > I've CCd Tim and Stefano for input from the HVM and QEMU sides.
> > >
> > > I think it is a good thing.
> > > The only thing to keep in mind is that QEMU upstream is switching to
> > > 16MB of videoram for stdvga. So at some point in the near future
> > > upstream QEMU will stop working correctly with xen 4.2, unless we
> bump
> > > the videoram to 16MB too.
> > >
> > Yes, we should pay attention to this when using upstream QEMU.
> >
> > >
> > > > > It's also a workaround for the following bug.
> > > > > http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1812
> > > >
> > > > Do you understand the root cause of that bug?
> > > >
> > I don't understand the root cause.
> >
> > > > It's hard to see how detaching a VF relates to the VGA emulation in
> use.
> > > > Can you explain it? Are you sure you aren't just masking the real issue
> > > > here?
> > >
> > It's strange that detaching a VF may break the graphics display.
> > As it only happens when 'stdvga=0', it might not be a normal usage.
> >
> > > Indeed. We cannot possibly accept the patch on the basis that it looks
> > > like it is masking an unrelated pci-passthrough bug.
> > >
> > I don't want to mask that bug, either. :-)
> > The following sentence is quoted from xl.cfg man page.
> > "If your guest supports VBE 2.0 or later (e.g. Windows XP onwards)
> > then you should enable this (stdvga option)."
> > If we set 'stdvga=1', we will not meet the bug (#1812).
> > I assume many Xen users (including me) are not very familiar with
> 'stdvga' and
> > will leave it as default (it's 0 before my patch).
> > If then, users may meet something *strange* like bug #1812.
> > I don't think it's friendly to end users, so I set the default value
> > of 'stdvga' to '1'.
> 
> There are good reasons which justify setting stdvga=1 by default. But
> anything to do with #1812 is not one of them. It is obviously wrong to
> justify making an unrelated configuration change on the basis that it
> hides a bug by default without first understanding the reasons for the
> bug.
> 
> I certainly hope you are not planning to close #1812 and stop
> investigating it if we change the stdvga default.
> 
Sure, I don't want to close bug #1812. As I'm not familiar with this, 
if someone want to fix it, I'll co-work with him/her about this issue. 
e.g. help to reproduce it or do some testing.