* Richard W.M. Jones (rjo...@redhat.com) wrote: > On Fri, Apr 01, 2016 at 10:24:37AM +0200, Paolo Bonzini wrote: > > On 01/04/2016 10:14, Richard W.M. Jones wrote: > > > Found it: only CONFIG_MPTABLE=y was necessary. It boots with: > > > > > > # CONFIG_PIRTABLE is not set > > > CONFIG_MPTABLE=y > > > # CONFIG_SMBIOS is not set > > > # CONFIG_ACPI is not set > > > > If you add all three it should not give any slowdown and will provide > > full hardware features to the kernel. qboot does ACPI and PCI bus > > assignment (it doesn't do SMBIOS because I got bored debugging it. :)) > > Enabling all 4 adds about 2ms. > > However the overhead of SeaBIOS is still down from 68ms to 18ms > (4.0% of total boot time down to 1.1%) so it's still a big gain. > > I wonder how we can make use of this in qemu and downstream distros? > Can we have a bios-min.bin which is used with -kernel boots?
Could we pass a flag at runtime that gets the standard image to skip a lot of the stuff you don't want? Or is there anything else qemu could provide (e.g. a fast way to get to PCI config space?) Dave -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
