Avi Kivity <avi@xxxxxxxxxx> writes: >> >> The issue with live migration is that we can't change the running >> >> configuration while the system is running, like adding the IMCR or >> >> changing the wiring. The hardware will be programmed for the old >> >> configuration and will likely fail with the new one. For example, the >> >> current wiring has the PIT output wired to PIC IRQ0 and IOAPIC INTI0; >> >> we need to change it to IOAPIC INTI2 instead. >> >> >> > >> > btw, I believe that the configuration currently implemented is legal >> > (it's similar to config 7 in table 5-2 of the mpspec); the only problem >> > is that it can't support the NMI watchdog through the I/O APIC trick, >> > yet we allow it through a hack. >> >> I'm confused a bit. "config 7 in table 5-2" says PIT output wired to >> IOAPIC INTIN2. So, we don't need to change it? > > We're like config 7 in that the 8259A output isn't wired to the IOAPIC. > However we're unlike config 7 in that the PIT output is wired to IOAPIC > INTIN0. I think we can keep it that way. > >> > Something we can do is connect the 8259A output to the I/O APIC INTIN2; >> > it should be masked so live migration will continue to work. We just >> > have to make sure that the guest is able to find that it is >> > connected there. >> >> 8259A INTR to IOAPIC INTIN2 sounds strange. Isn't it IOAPIC INTIN0? > > Usually yes, but we already have the PIT wired to INTIN0. I saw that > the kernel consults the mptable to see which pin to use, so with the > right BIOS magic we can get things to work. Um..., I'm confused more. If so, MADT doesn't say it. MADT says irq == 0 is pin == 2, this is one of reasons why linux is quite silent in check_timer(). And I can't see why it is working by pin == 2 for IOAPIC. If I can make time, I'll see what happens by pin == 2 and pin == 0 of IOAPIC in kvm. Thanks. -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
