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Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the ba
From: |
Ian Campbell |
Subject: |
Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI |
Date: |
Wed, 27 Feb 2013 11:06:53 +0000 |
I'm not sure about qemu-devel but on xen-devel the policy is not to top
post so please could you avoid doping so.
On Wed, 2013-02-27 at 09:49 +0000, Zhang, Xiantao wrote:
> > Given that Xen has at least two other mechanisms (xenstore and
> > hvmparams) for passing this sort of information around I'm not sure why
> > hacking the emulated i440fx device should be the preferred option.
>
> Actually, even in hardware, I believe there are many registers which
> are implemented with write-once attributes, and they are only used by
> firmware and reserved for OS.
The i440fx does not have this register (be it write once or otherwise),
which is my actual point -- you are adding a magic property to the
emulation of this device which the real hardware doesn't have. It isn't
really relevant that other hardware could implement write once
registers, that's obviously the case.
> In addition, with this change, it can benefit all VMMs (not just
> Xen) which use Qemu as device model. If adopt xenstore way, perhaps
> other VMMs also have to write similar and duplicate logic for the same
> purpose.
Which other VMM? AIUI qemu/kvm doesn't have a requirement to communicate
this information from the VMM to qemu because qemu is the VMM and
controls all of the hardware resources.
Ian.
- [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Xudong Hao, 2013/02/25
- Re: [Qemu-devel] [Xen-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Ian Campbell, 2013/02/25
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Stefano Stabellini, 2013/02/25
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Hao, Xudong, 2013/02/25
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Zhang, Xiantao, 2013/02/26
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Stefano Stabellini, 2013/02/26
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Ian Campbell, 2013/02/26
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Anthony Liguori, 2013/02/26
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Zhang, Xiantao, 2013/02/27
- Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI,
Ian Campbell <=
Re: [Qemu-devel] [PATCH v2] piix: define a TOM register to report the base of PCI, Michael S. Tsirkin, 2013/02/27