On 07/12/18 14:58, Juergen Gross wrote: > On 07/12/2018 14:52, Paolo Bonzini wrote: >> On 07/12/18 14:50, Juergen Gross wrote: >>> The PVH boot entry is in the same bzImage binary as the normal one. >>> Its just another entry, similar to the Xen PV boot entry. So the binary >>> arch/x86/boot/bzimage can be booted either on bare metal via grub2 or >>> other boot-loaders, as Xen PV-guest, as Xen PVH-guest, or as KVM >>> PVH-guest. So one build and one binary. The non-standard boot entries >>> (PV- or PVH-node) are found via ELF-notes by the boot loader (qemu in >>> case of KVM). >> >> But the bzImage is not an ELF binary, and it is compressed, isn't it? >> /me is confused. :) > > grub2 (and qemu, too) can decompress it. And the decompressed result > "vmlinux" is an ELF-binary. Aha - for KVM, the main advantage of PVH would be to skip the cost of decompression, and that is what confused me (also we probably prefer not having any decompression code running in QEMU, since that increases the attack surface; there's no real disadvantage to using the existing linuxboot code if we're given a bzImage). So, at least for now, KVM would go with the two-binaries/one-config approach. Sorry for having you lecture me, it's much clearer now. Thanks, Paolo
