On Mon, Oct 10, 2011 at 06:08:03PM +0100, Daniel P. Berrange wrote: > I've been investigating where time disappears to when booting Linux guests. > > Initially I enabled DEBUG_BIOS in QEMU's hw/pc.c, and then hacked it so > that it could print a timestamp before each new line of debug output. The > problem with that is that it slowed down startup, so the timings I was > examining all changed.
A lot of effort went into optimizing SeaBIOS boot time. There is a tool in seabios git to help with benchmarking - tools/readserial.py. The tool was designed for use with serial ports on real machines using coreboot, but it works with qemu too: mkfifo seabioslog ./tools/readserial.py -nf seabioslog qemu-system-x86_64 -chardev pipe,id=seabios,path=seabioslog -device isa-debugcon,iobase=0x402,chardev=seabios -hda myimage This will show the SeaBIOS debug output with timing info. -Kevin
