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Re: [Qemu-devel] [RFC] virtio: Report new guest memory statistics pertin
From: |
Adam Litke |
Subject: |
Re: [Qemu-devel] [RFC] virtio: Report new guest memory statistics pertinent to memory ballooning (V2) |
Date: |
Mon, 09 Nov 2009 13:16:14 -0600 |
On Mon, 2009-11-09 at 19:00 +0000, Jamie Lokier wrote:
> Adam Litke wrote:
> > + s->stats.pswapin = has_feature(dev, VIRTIO_BALLOON_F_RPT_SWAP_OUT)
> > ?
> > + dev->stats.pswapin : -1;
>
> (etc.)
>
> Why not simply have the guest fill in the unused fields with -1, and
> say that's how "no meaningful value" is represented in the ABI?
>
> All guests have to know about all those fields anyway, for the
> structure layout. Is there any benefit to specifying feature bits in
> advance over simply storing -1 there?
This holds true for fields that exist but might not be supported by a
guest, but what about the case where we add a new field? In that case,
qemu and the guest may disagree on the structure layout.
--
Thanks,
Adam
- Re: [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, (continued)
- Re: [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Rusty Russell, 2009/11/10
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Anthony Liguori, 2009/11/10
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Rusty Russell, 2009/11/10
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Anthony Liguori, 2009/11/10
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Rusty Russell, 2009/11/10
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Adam Litke, 2009/11/11
- [Qemu-devel] Re: virtio: Add memory statistics reporting to the balloon driver, Rusty Russell, 2009/11/11
Re: [Qemu-devel] [RFC] virtio: Report new guest memory statistics pertinent to memory ballooning (V2), Jamie Lokier, 2009/11/09
Re: [Qemu-devel] [RFC] virtio: Report new guest memory statistics pertinent to memory ballooning (V2), Jamie Lokier, 2009/11/09