On 05/12/18 23:31, Liam Merwick 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 with minimal firmware involvement. > > 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/pvh.html > > Details on the Linux changes: https://lkml.org/lkml/2018/4/16/1002 > > This patch series provides qboot support to populate the start_info struct > needed by the direct boot ABI and to configure the guest e820 tables to > enable QEMU to use that same entry point for booting KVM guests. > > Usіng the methods/scripts documented by the NEMU team at > > https://github.com/intel/nemu/wiki/Measuring-Boot-Latency > https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg00200.html > > below are some timings measured (vmlinux and bzImage from the same build). > Time to get to kernel start is almost halved (95ṁs -> 48ms)
I had a few comments on patch 2, but overall it looks fine. Can you send a pull request on GitHub? Thanks, Paolo > QEMU + qboot + vmlinux (PVH + 4.20-rc4) > qemu_init_end: 41.550521 > fw_start: 41.667139 (+0.116618) > fw_do_boot: 47.448495 (+5.781356) > linux_startup_64: 47.720785 (+0.27229) > linux_start_kernel: 48.399541 (+0.678756) > linux_start_user: 296.952056 (+248.552515) > > QEMU + qboot + bzImage: > qemu_init_end: 29.209276 > fw_start: 29.317342 (+0.108066) > linux_start_boot: 36.679362 (+7.36202) > linux_startup_64: 94.531349 (+57.851987) > linux_start_kernel: 94.900913 (+0.369564) > linux_start_user: 401.060971 (+306.160058) > > QEMU + bzImage: > qemu_init_end: 30.424430 > linux_startup_64: 893.770334 (+863.345904) > linux_start_kernel: 894.17049 (+0.400156) > linux_start_user: 1208.679768 (+314.509278) > > > Liam Merwick (3): > pvh: Add x86/HVM direct boot ABI header file > pvh: use x86/HVM direct boot ABI > pvh: add benchmark exit point > > benchmark.h | 3 +- > fw_cfg.c | 79 +++++++++++++++++++++++++++- > include/start_info.h | 146 > +++++++++++++++++++++++++++++++++++++++++++++++++++ > linuxboot.c | 2 +- > main.c | 3 ++ > tables.c | 9 ++++ > 6 files changed, 239 insertions(+), 3 deletions(-) > create mode 100644 include/start_info.h >
