Re: [Xen-devel] [RFC XEN PATCH v4 33/41] tools/libacpi, hvmloader: detect QEMU fw_cfg interface

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 03/02/18 11:26 +0000, Anthony PERARD wrote:
> On Wed, Feb 28, 2018 at 05:17:23PM +0800, Haozhong Zhang wrote:
> > On 02/27/18 17:37 +0000, Anthony PERARD wrote:
> > > On Thu, Dec 07, 2017 at 06:10:22PM +0800, Haozhong Zhang wrote:
> > > > Add a function in libacpi to detect QEMU fw_cfg interface. Limit the
> > > > usage of fw_cfg interface to hvmloader now, so use stub functions for
> > > > others.
> > > 
> > > I think libacpi is not the right place for a driver. The fw_cfg driver
> > > would be better in hvmloader.
> > 
> > Yes, I can move it to hvmloader. My original thought was it might be
> > reused (by replacing those stub functions) when someone wants to add
> > vNVDIMM support to PVH domU and still use QEMU as the device model
> > for vNVDIMM.
> 
> :(, I don't see how the fw_cfg drivers could be reuse in a PVH guest,
> right now. It is only usefull when runned from inside the guest. So far,
> I think libacpi is use in Xen, maybe libxl and hvmloader.
> 
> If QEMU's fw_cfg was available within a PVH guest, I guess we could use
> hvmloader, or teach OVMF to merge the tables from Xen and QEMU, or maybe
> GRUB or Linux could learn about fw_cfg.
> 
> Anyway, I think for now, the fw_cfg drivers is better in hvmloader, and
> we can move the code later if/when needed.
>

You are right, I'll move it to hvmloader.

> > > As to copy the ACPI tables from fw_cfg to libacpi, maybe the passthrough
> > > tables (or an improvement of it) could be use. (It is already to to add
> > > extra tables from libxl (HVM_XS_ACPI_PT_ADDRESS).)
> > >
> > 
> > They are doing the same job (transferring guest ACPI from host to
> > guest) in two quite different ways, rather than two pieces of jobs not
> > completely overlap, so I think it's hard to let them collaborate with
> > each other. Do you have any idea in mind?
> 
> I don't really have an idea in mind. I guess it is going to depends of
> what libacpi have to do, once the fw_cfg drivers have done the jobs of
> loading the ACPI tables in memory.
> 
> Thanks,
> 
> -- 
> Anthony PERARD
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel