Balloon driver for Linux/HVM

Balloon driver for Linux/HVM

[Rui Chu]

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Hi,
I have noticed that, in the code of linux/drivers/xen/balloon.c, there exists the snippet as this:

static int __init balloon_init(void)
{
unsigned long pfn;
struct page *page;
if (!xen_pv_domain())
return -ENODEV;
.....
}

Does it means the driver will not work in HVM? If so, where is the HVN-enabled code for that?

2010-11-16 



Rui Chu 

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Balloon driver for Linux/HVM

[Chu Rui]

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Hi,
I have noticed that, in the code of linux/drivers/xen/balloon.c, there
exists the snippet as this:

 static int __init balloon_init(void)
{
unsigned long pfn;
struct page *page;
 if (!xen_pv_domain())
return -ENODEV;
.....
}

Does it means the driver will not work in HVM? If so, where is the
HVN-enabled code for that?

2010-11-16
------------------------------
Rui Chu

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Re: Balloon driver for Linux/HVM

[Stefano Stabellini]

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On Tue, 16 Nov 2010, Chu Rui wrote:
> Hi,
> I have noticed that, in the code of linux/drivers/xen/balloon.c, there exists the snippet as this:
>  
> static int __init balloon_init(void)
> {
> unsigned long pfn;
> struct page *page;
> if (!xen_pv_domain())
> return -ENODEV;
> .....
> }
>  
> Does it means the driver will not work in HVM? If so, where is the HVN-enabled code for that?

not yet, even though I have a patch ready to enable it:

git://xenbits.xen.org/people/sstabellini/linux-pvhvm.git 2.6.36-rc7-pvhvm-v1

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Re: Balloon driver for Linux/HVM

[Jeremy Fitzhardinge]

On 11/22/2010 01:51 AM, Daniel Kiper wrote:
> Hi,
>
> On Thu, Nov 18, 2010 at 12:32:35PM -0800, Dan Magenheimer wrote:
>> What is the difference between 2.6.36 balloon driver and Jeremy's
>> xen/balloon tree head?  I think ideally the kernel version for
>> development should be the latest (2.6.36).
> I know that the best practice is to base new work on the
> latest stable kernel version, however I am not sure that it is
> the case there. xen/balloon head contains most of neweset fixes
> and improvments which are not merged into current stable till
> now. That is why I think we should start from this and later
> merge it with current stable. However, maybe Jeremy may have
> better view of which version would be better for the start
> of development.
>

The big difference between xen/balloon and current mainline is hugepage
support, which is not yet in an upstreamable state.  Aside from that,
current upstream balloon driver (in current git, post 2.6.37-rc3) is
equivalent, and would make a good base for development.

The main difference between .37-rc and .36 is support for boot-time
ballooning, but the changes to the balloon driver to support that are
small, so .36 would probably make a reasonable base as well.

    J

Re: Balloon driver for Linux/HVM

[Daniel Kiper]

Hi,

Sorry for late reply, however I am very busy now.

On Wed, Nov 24, 2010 at 10:53:58AM -0800, Jeremy Fitzhardinge wrote:
> On 11/22/2010 01:51 AM, Daniel Kiper wrote:
> > Hi,
> >
> > On Thu, Nov 18, 2010 at 12:32:35PM -0800, Dan Magenheimer wrote:
> >> What is the difference between 2.6.36 balloon driver and Jeremy's
> >> xen/balloon tree head?  I think ideally the kernel version for
> >> development should be the latest (2.6.36).
> > I know that the best practice is to base new work on the
> > latest stable kernel version, however I am not sure that it is
> > the case there. xen/balloon head contains most of neweset fixes
> > and improvments which are not merged into current stable till
> > now. That is why I think we should start from this and later
> > merge it with current stable. However, maybe Jeremy may have
> > better view of which version would be better for the start
> > of development.
> >
>
> The big difference between xen/balloon and current mainline is hugepage
> support, which is not yet in an upstreamable state.  Aside from that,
> current upstream balloon driver (in current git, post 2.6.37-rc3) is
> equivalent, and would make a good base for development.
>
> The main difference between .37-rc and .36 is support for boot-time
> ballooning, but the changes to the balloon driver to support that are
> small, so .36 would probably make a reasonable base as well.

Thx. I will prepare patches for 2.6.36.

Daniel