Hi Samuel, Rob, I'm proceeding to compare several x86 firmwares in order to understand which suits better with -kernel option to have a fast boot with QEMU/NEMU.
For your use cases, what boot time do you expect? I compared SeaBIOS, qboot, and OVMF. I started each test using this qemu parameters: "./qemu-system-x86_64 -bios path/to/bios.bin -m 1G -cpu host -M accel=kvm -vga none -kernel path/to/bzImage -initrd path/to/rootfs.cpio ..." As Samuel suggested, I added the total time to userspace adding a probe in the kernel_init(), so the times (in msec) that I measured are: - qemu_init_end: first kvm_entry (i.e. QEMU initialized has finished) - fw_start: first entry of the firmware - fw_do_boot: after the firmware initialization (e.g. PCI setup, etc.) - linux_start_boot: before the jump to the Linux kernel - linux_start_user: before starting the init process * SeaBIOS Default configuration without debug messages (CONFIG_DEBUG_LEVEL=0) + Stephen's patch (tpm: Check for TPM related ACPI tables before attempting hw) + my patch (qemu: fast boot when linuxboot optionrom is used). qemu_init_end: 41.634812 fw_start: 41.857374 (+0.222562) fw_do_boot: 52.754109 (+10.896735) linux_start_boot: 54.117220 (+1.363111) linux_start_user: 495.684199 (+441.566979) * qboot Default configuration + my patch (pci: reduce pci_foreach() calls). qemu_init_end: 40.233717 fw_start: 40.384048 (+0.150331) fw_do_boot: 45.660497 (+5.276449) linux_start_boot: 47.252119 (+1.591622) linux_start_user: 509.173886 (+461.921767) * OVMF (https://github.com/intel/ovmf-virt) I followed this script (https://github.com/intel/nemu/blob/topic/virt-x86/tools/CI/run_nats.sh) to build OVMF. Note: I put the "fw_start" probe in the BdsEntry() [MdeModulePkg/Universal/BdsDxe/BdsEntry.c], I'm not sure if it is "near" to the real entry point. qemu_init_end: 42.734555 fw_start: 163.611506 (+120.876951) fw_do_boot: 369.713760 (+206.102254) linux_start_boot: 370.960364 (+1.246604) linux_start_user: 796.799667 (+425.839303) For OVMF case, are reasonable the times that I measured? Do you use a different configuration? Thanks, Stefano -- Stefano Garzarella Red Hat
