On Fri, Apr 01, 2016 at 09:44:56AM +0100, Richard W.M. Jones 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.
CONFIG_SMBIOS and CONFIG_ACPI only control the legacy internal bios tables. One would disable CONFIG_FW_ROMFILE_LOAD to disable the newer ACPI tables; there is no config option currently to disable the newer smbios tables. These config names are a bit misleading, so they probably should be changed in seabios. I didn't expect disabling the above options to do anything besides reduce the size of the seabios binary, so I'm a bit suprised it saved 2ms. Did you have something on your qemu command-line to avoid generating acpi/smbios tables? -Kevin