Re: [Xen-devel] [RFC] OVMF on PVH

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.08.18 at 13:24, <anthony.perard@xxxxxxxxxx> wrote:
> ## New binary, separated from QEMU/KVM one.
> 
> Right now, the rules to build the firmware are located in
> `OvmfPkg/OvmfPkgX64.dsc`, a platform. I've created a new platform, without
> KVM support, and would like to retire the Xen support from the current
> platform.  For now, I have created OvmfPkg/XenOvmf.dsc. (The change to a
> new platform had been proposed by upstream.)
> 
> That would simplify Xen support in OVMF, and allow to diverge more from
> OVMF where needed. That would mostly be useful during the initial boot
> phase where there lots of `if xen do that, else do that`.
> 
> We can also choose some drivers that can work on both PVH and HVM, for
> example, use a LAPIC timer instead of ACPI Timer.
> 
> All this mean that building OVMF for Xen would need to be change.

And users / tool stacks having to pick the right binary.

> ## Loading binary at 0x10000 (1MB, like hvmloader on HVM)
> 
> Right now, the OVMF blob is loaded (by hvmloader) just below 4GB, with
> hvmloader moving some RAM around to allow that.  But with the use of an
> ELF header, and let libxc load the blob, it was not possible to load the
> blob just below 4GB. (Or at least without modification of the toolstack I
> guess.) So I've attempted to have OVMF been started from a different place
> in memory. Then I had to hack a bit more in order to be able to start OVMF
> from two different location (the current one for HVM guest, and a new one
> that can be used for PVH). That works fine, I'll just have to find out
> what upstream think about that.

I'm of two minds here - as a firmware binary, it doesn't seem to make
sense to load at 0x100000, yet as a hvmloader replacement it might.
However, parts of it will need to stay (runtime services code/data),
and such permanent data better lives at higher addresses imo.

Jan



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