On Thu, 2008-05-15 at 20:51 -0400, Vivek Goyal wrote:
> On Thu, May 15, 2008 at 01:41:50PM +0800, Huang, Ying wrote:
> > Hi, Vivek,
> >
> > On Wed, 2008-05-14 at 16:52 -0400, Vivek Goyal wrote:
> > [...]
> > > Ok, I have done some testing on this patch. Currently I have just
> > > tested switching back and forth between two kernels and it is working for
> > > me.
> > >
> > > Just that I had to put LAPIC and IOAPIC in legacy mode for it to work. Few
> > > comments/questions are inline.
> >
> > It seems that for LAPIC and IOAPIC, there is
> > lapic_suspend()/lapic_resume() and ioapic_suspend()/ioapic_resume(),
> > which will be called before/after kexec jump through
> > device_power_down()/device_power_up(). So, the mechanism for
> > LAPIC/IOAPIC is there, we may need to check the corresponding
> > implementation.
> >
>
> ioapic_suspend() is not putting APICs in Legacy mode and that's why
> we are seeing the issue. It only saves the IOAPIC routing table entries
> and these entries are restored during ioapic_resume().
>
> But I think somebody has to put APICs in legacy mode for normal
> hibernation also. Not sure who does it. May be BIOS, so that during
> resume, second kernel can get the timer interrupts.
As for IOAPIC legacy mode, is it related to the following code which set
the routing table entry for i8259?
void disable_IO_APIC(void)
{
/*
* Clear the IO-APIC before rebooting:
*/
clear_IO_APIC();
/*
* If the i8259 is routed through an IOAPIC
* Put that IOAPIC in virtual wire mode
* so legacy interrupts can be delivered.
*/
if (ioapic_i8259.pin != -1) {
struct IO_APIC_route_entry entry;
memset(&entry, 0, sizeof(entry));
entry.mask = 0; /* Enabled */
entry.trigger = 0; /* Edge */
entry.irr = 0;
entry.polarity = 0; /* High */
entry.delivery_status = 0;
entry.dest_mode = 0; /* Physical */
entry.delivery_mode = dest_ExtINT; /* ExtInt */
entry.vector = 0;
entry.dest.physical.physical_dest =
GET_APIC_ID(apic_read(APIC_ID));
/*
* Add it to the IO-APIC irq-routing table:
*/
ioapic_write_entry(ioapic_i8259.apic, ioapic_i8259.pin,
entry);
}
disconnect_bsp_APIC(ioapic_i8259.pin != -1);
}
But, because IOAPIC may need to be in original state during
suspend/resume, so it is not appropriate to call disable_IO_APIC() in
ioapic_suspend(). So I think we can call disable_IO_APIC() in new
hibernation/restore callback.
Am I right?
Best Regards,
Huang Ying
_______________________________________________
linux-pm mailing list
linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/linux-pm
