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[Xen-devel] VIRQ_CON_RING

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Subject: [Xen-devel] VIRQ_CON_RING
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 12 Nov 2009 14:19:32 +0000
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Is there any real user for this vIRQ? I'm asking because, while debugging
a problem that required to add some printk()s that could temporarily issue
at a high rate, I ran into the situation that this extra output prevented
guest/dom0 boot from making any progress. As I then realized this was
due to the tasklet_schedule() called from inside the console handling
code, which resulted in subsequent hypercall_preempt_check() to force
exit (after creating a continuation) from the respective hypercall handler

While I realize that for compatibility reasons (even in the case of there
not being a current user) it may not be possible to drop this vIRQ
altogether, I wonder whether it would be possible to avoid scheduling
the tasklet when the vIRQ has no handler and/or is already pending.


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