Re: [Xen-devel] [PATCH v2 1/1] tools: Handle xc_maxmem adjustments

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 14/04/15 23:06, Don Slutz wrote:
> This fixes an issue where "xl save" followed by "xl restore" reports:
> "xc: error: Failed to allocate memory for batch.!: Internal error"
>
> One of the ways to get into this state is to have more then 4 e1000
> nics configured.
>
> Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>

I still don't think this is the correct solution, although I will
concede that this is a far better patch than v1.

Going back to the original problem, why does Qemu need to change maxmem
in the first place?  You talk about e1000 option roms, but the option
roms themselves must be allocated in an appropriate PCI bridge window.

As a result, there is necessarily already ram backing, which can be
ballooned back in.  Currently, all ram behind the PCI MMIO is ballooned
out hvmloader but still accounted to the domain, and otherwise wasted.

~Andrew

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