Messages in this thread | | | Date | Wed, 29 Apr 2009 11:18:47 +0300 | From | Avi Kivity <> | Subject | Re: [KVM PATCH v3 0/2] irqfd |
| |
Andrew Morton wrote: > On Mon, 27 Apr 2009 14:33:24 -0400 Gregory Haskins <ghaskins@novell.com> wrote: > > >> (Applies to kvm.git 41b76d8d0487c26d6d4d3fe53c1ff59b3236f096) >> >> This series implements a mechanism called "irqfd". It lets you create >> an eventfd based file-desriptor to inject interrupts to a kvm guest. We >> associate one gsi per fd for fine-grained routing. >> > > It'd be nice if the KVM weenies amongst us were to be told why one > would want to inject interrupts into a KVM guest. Monosyllabic words > would be preferred ;) >
Interrupts are injected (better word, raised) into a guest because real hardware has interrupts. This patchset does not add the ability to raise interrupts (that existed from day 1); it adds an eventfd interface to do so.
An eventfd interface is useful, because it allows components to talk to kvm guests without being tied to kvm internals; they signal an eventfd; if the eventfd is terminated in kvm, it injects an interrupt. If the eventfd is terminated in userspace, it returns from epoll().
>> We do not have a user of this interface in this series, though note >> future version of virtual-bus (v4 and above) will be based on this. >> > > So I assume that this patchset will be merged if/when a user of it is > merged? >
This interface is applicable to both the kernel and userspace; userspace users won't be merged.
But I certainly want to see how the whole thing works.
>> The first patch will require mainline buy-in, particularly from Davide >> (cc'd). The last patch is kvm specific. >> > > Three EXPORT_SYMBOL_GPL()s. Once the shouting has subsided I'd suggest > that this be merged via the KVM tree. >
I think eventfd makes tons of sense as a generic 'wake me up' mechanism that can be used from both sides of the kernel/user line.
-- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
| |