On Thu, 20 Oct 2016 16:51:48 -0200
Eduardo Habkost <ehabk...@redhat.com> wrote:
> On Thu, Oct 20, 2016 at 04:58:42PM +0200, Igor Mammedov wrote:
> > Currently firmware uses 1 byte at 0x5F offset in RTC CMOS
> > to get number of CPUs present at boot. However 1 byte is
> > not enough to handle more than 255 CPUs. So add a new
> > fw_cfg file that would allow QEMU to tell it.
> > For compat reasons add file only for machine types that
> > support more than 255 CPUs.
> >
> > Signed-off-by: Igor Mammedov <imamm...@redhat.com>
>
> I suggest squashing this into the patch, to clarify why we are
> setting it to 0.
>
> Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
Could you squash it in while merging series?
> ---
> hw/i386/pc.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index c6f6747..a03b384 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1225,6 +1225,10 @@ static void
> pc_build_feature_control_file(PCMachineState *pcms)
> static void rtc_set_cpus_count(ISADevice *rtc, uint16_t cpus_count)
> {
> if (cpus_count > 0xff) {
> + /* If the number of CPUs can't be represented in 8 bits, the
> + * BIOS must use "etc/boot-cpus". Set RTC field to 0 just
> + * to make old BIOSes fail more predictably.
> + */
> rtc_set_memory(rtc, 0x5f, 0);
> } else {
> rtc_set_memory(rtc, 0x5f, cpus_count - 1);
