Re: [Qemu-devel] [Xen-devel] [PATCH v2] piix: define a TOM register to report the base of PCI

[Ian Campbell]

On Mon, 2013-02-25 at 06:53 +0000, Xudong Hao wrote:
> v2:
> * Use "piix: " in the subject rather than "qemu: "
> * Define TOM register as one byte
> * Define default TOM value instead of hardcode 0xe0000000 in more that one 
> place
> * Use API pci_set_byte for pci config access
> * Use dev->config instead of the indirect d->dev.config
> 
> Define a TOM(top of memory) register to report the base of PCI memory, update
> memory region dynamically. TOM register are defined to one byte in PCI 
> configure
> space, because that only upper 4 bit of PCI memory takes effect for Xen, so
> it requires bios set TOM with 16M-aligned.

Is it really OK to just add registers to the PIIX like this? This is
supposed to be emulating an actual real life device after all.

Perhaps an HVM param or some other out of band mechanism would be better
here?

Ian.