Messages in this thread | | | Date | Fri, 10 Apr 2009 14:27:50 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC -tip] x86: do_IRQ - send APIC EOI for x86-32 on irq without handler v3 |
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* Cyrill Gorcunov <gorcunov@openvz.org> wrote:
> Ingo, I've checked the sources and as far as I see > we could NOP'ify apic->write indeed but I have > an internal feeling that this will bring us more problem > in future (for example it could be the following scenario: > some screwed APIC would require cleaning of LVT's or > IRR after resume regardless if it was initialized > or not at all). Mostly I mean that the idea of making > apic->write NOP'ified is quite elegant indeed but > cut off the subset of apic operations (we need > apic->read anyway) somehow bothering me from inside :)
it's as if assigned a special type of 'dummy apic' struct apic. It wont cause problems down the line: we use the new APIC driver infrastructure to abstract out quirks.
one small detail:
> +/* Ack APIC irq if it's enabled only */ > +static inline void ack_APIC_irq_safe(void) > +{ > +#ifdef CONFIG_X86_LOCAL_APIC > + if (cpu_has_apic) > + ack_APIC_irq(); > +#endif
we dont need the cpu_has_apic check there, do we? In the !cpu_has_apic the ->write method should be a dummy.
> -#ifdef CONFIG_X86_64 > - if (!disable_apic) > - ack_APIC_irq(); > -#endif > - > + ack_APIC_irq_safe();
Please keep the ack_APIC_irq() name - it is inherently safe to call it if we always give it a meaningful ->write method.
Ingo
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