Re: [Xen-devel] fooey. no interrupts.

[ron minnich <rminnich@xxxxxxxx>]

On Mon, 9 Aug 2004, Keir Fraser wrote:

> 
> The Linux code sets the evtchn_mask before clearing evtchn_pending,
> then clears the evtchn_mask after calling the interrupt handler. Are
> you doing the setting but forgetting the clearing?

sadly, no. 

> 
> The order that Linux has for this stuff, to avoid races, is:
> 
>  1. Test-and-clear evtchn_upcall_pending flag
>  2. Read-and-clear (XCHG) the evtchn_pending_sel
>  3. For each set bit @i in the sel:
>  4.   Read evtchn_pending[@i]
>  5.   For each set bit @j in the word:
>  6.     Set evtchn_mask[@i*32+@j]
>  7.     Clear evtchn_pending[@i*32+@j]
>  8.     ....do interrupt work...
>  9.     Clear evtchn_msk[@i*32+@j]

yeah, I'm actually using that code. 

oh well.

ron

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