Re: [Xen-devel] [PATCH 0 of 4] videoram allocation and stdvga improvements

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Stefano Stabellini, le Wed 14 Jan 2009 19:00:38 +0000, a écrit :
> Samuel Thibault wrote:
> 
> > Samuel Thibault, le Tue 13 Jan 2009 15:01:08 +0100, a écrit :
> >> Stefano Stabellini, le Tue 13 Jan 2009 12:17:47 +0000, a écrit :
> >>> In order to simplify the codepath and the libxc API, this patch series
> >>> removes the videoram allocation code from hvmloader and lets qemu do the
> >>> job, using xc_domain_memory_populate_physmap.
> >> That's what it was doing before I made hvmloader do it.  The reason was
> >> to make save/restore work fine with stubdomains dirty log, etc.
> > 
> > Ah, now I remember the precise reason, written in the 18383 changelog:
> > 
> > When creating an HVM domain, if e.g. another domain is created before
> > qemu allocates video memory, the extra 8MB memory ballooning is not
> > available any more, because it got consumed by the other domain.
> > 
> 
> The current design of the autoballoner is limited, as a consequence the
> autoballoner is racy and it should not be used at all if the user plans
> to start multiple domains at the same time.

The problem is that with stubdomain-based qemu you _always_ start
multiple domains at the same time.

Samuel

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