On 11/29/2017 12:59 AM, Paolo Bonzini wrote:
On 28/11/2017 20:34, Maran Wilson wrote:For certain applications it is desirable to rapidly boot a KVM virtual machine. In cases where legacy hardware and software support within the guest is not needed, Qemu should be able to boot directly into the uncompressed Linux kernel binary without the need to run firmware. There already exists an ABI to allow this for Xen PVH guests and the ABI is supported by Linux and FreeBSD: https://xenbits.xen.org/docs/unstable/misc/hvmlite.html This PoC patch enables Qemu to use that same entry point for booting KVM guests.Nice! So QEMU would parse the ELF file just like for multiboot, find the ELF note, and then prepare an hvmlite boot info struct instead of the multiboot one?
Yes, exactly.
There would then be a new option ROM, very similar to multiboot.S.
That is one option. I guess this gets into a discussion about the QEMU side of the upcoming patches that would follow ...
I'm currently just initializing the CPU state in QEMU for testing since there is such minimal (non Linux specific) setup that is required by the ABI. And (borrowing from the Intel clear container patches) that VM setup is only performed when user selects the "nofw" option with the q35 model. But yeah, if folks think it important to move all such machine state initialization out of QEMU and into an option ROM, I can look into coding it up that way for the QEMU patches.
Thanks, -Maran
Thanks, Paolo
