Andrew Morton wrote: > On Thu, 19 Oct 2006 17:09:22 -0700 > Zachary Amsden <zach at vmware.com> wrote: > > >> Add a way to disable the timer IRQ routing check via a boot option. The >> VMI timer code uses this to avoid triggering the pester Mingo code, which >> probes for some very unusual and broken motherboard routings. It fires >> 100% of the time when using a paravirtual delay mechanism instead of >> using a realtime delay, since there is no elapsed real time, and the 4 timer >> IRQs have not yet been delivered. >> >> In addition, it is entirely possible, though improbable, that this bug >> could surface on real hardware which picks a particularly bad time to enter >> SMM mode, causing a long latency during one of the timer IRQs. >> >> While here, make check_timer be __init. >> >> > > Andi seems to have merged this patch but from somewhere I picked up a > different version, below. > > I think the version I have is better. Because the patch Andi has merged is > cast in terms of "irq testing", which is broad. But that's not what the > patch does - the patch handles only timers. > > IOW, this: > > >> + >> + noirqtest [IA-32,APIC] Disables the code which tests for broken >> + timer IRQ sources. >> > > is misleadingly named. This: > > + no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for > + broken timer IRQ sources. > + > > is better, no? > > But right now, I'll settle for anything which usually compiles. > > Yes, the name sucks. There is no real reason to actually have a boot parameter at all once the paravirt / VMI patches are in, but I wanted something to be able to set timer_irq_really_works until then to avoid someone accidentally removing it. Zach
