[Qemu-devel] Re: [PATCH] HPET fixes for reg writes

[Andriy Gapon]

on 24/07/2009 19:26 Beth Kon said the following:
> This patch addresses the problems found by Andriy Gapon: 
> 
> - The code was incorrectly overwriting the high order 32 
>   bits of the timer and hpet config registers. This didn't show up
>   in testing because linux and windows use hpet in legacy mode,
>   where the high order 32 bits (advertising available interrupts)
>   of the timer config register are ignored, and the high order 32
>   bits of the hpet config register are reserved and unused.
> 
> 
> - The mask for level-triggered interrupts was off by a bit. (hpet
>   doesn't currently support level-triggered interrupts).
> 
> In addition, I removed some unused #defines, and corrected the ioapic
> interrupt values advertised. I'd set this up early in hpet development
> and never went back to correct it, and no bugs resulted since linux and
> windows use hpet in legacy mode where available interrupts are ignored.
> 

Beth,

thanks a lot!

And a comment: it seems that the code doesn't verify interrupt configured by
software, it happily uses any interrupt even if it's not advertised in interrupt
capabilities. I know, the software should not do that, but it happens :)

Also, maybe it would be a good idea to keep support for some additional
interrupts? E.g. irq 10, 11 or some such, or maybe something >= 16 for APIC mode
(if possible at all). But I know that this needs some careful thinking to not
interfere with other emulated devices.

-- 
Andriy Gapon