Re: [Xen-devel] [PATCH v4 1/9] libxc: reorganize domain builder guest memory allocator

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Nov 12, 2015 at 12:29:06PM +0100, Juergen Gross wrote:
> On 12/11/15 12:20, Ian Campbell wrote:
> > On Thu, 2015-11-12 at 11:14 +0000, Wei Liu wrote:
> >> On Thu, Nov 05, 2015 at 03:36:27PM +0100, Juergen Gross wrote:
> >>> Guest memory allocation in the domain builder of libxc is done via
> >>> virtual addresses only. In order to be able to support preallocated
> >>> areas not virtually mapped reorganize the memory allocator to keep
> >>> track of allocated pages globally and in allocated segments.
> >>>
> >>> This requires an interface change of the allocate callback of the
> >>> domain builder which currently is using the last mapped virtual
> >>> address as a parameter. This is no problem as the only user of this
> >>> callback is stubdom/grub/kexec.c using this virtual address to
> >>> calculate the last used pfn.
> >>>
> >>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >>
> >> One question: did you test building with pygrub after this change? I
> >> think the code is correct but we'd better be sure it doesn't break
> >> pygrub.
> > 
> > Did you mean pvgrub? (with a Vee)
> > 
> > pygrub (with a Why) runs way before the libxc domain builder gets in on the
> > act, doesn't it.
> 
> Yep.
> 
> To be clear: we have:
> 
> - pygrub: running on dom0, mounts the root disk and analyzes the grub
>   configuration found, selects kernel and initrd and loads those via
>   libxl.
> 
> - pvgrub: based on grub2, is started via libxl as paravirtualized kernel
>   in the new domain. pvgrub is reading the grub configuration and starts
>   the appropriate kernel via it's own mechanisms (patches for support of
>   huge domains are sent, no comments up to now).
> 
> - stubdom based grub: subject to the patch we are discussing here. It is
>   being built in my environment, but not tested up to now.
> 
> 

I think we use pvgrub to denote the third case (according to our wiki).
The second case is just ... upstream grub2 with pv capability ?

(So many grubs...)

> Juergen
> 

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