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Re: [Qemu-devel] eventfd_signal()
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] eventfd_signal() |
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Date: |
Fri, 08 May 2015 13:32:11 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 08/05/2015 13:24, Paolo Bonzini wrote:
>
>
> On 08/05/2015 12:58, Catalin Vasile wrote:
>> Is eventfd blocking? By that I mean: If I signal the guest for
>> something, will that thread remain blocked till the guest clears the
>> interrupt?
>
> No. If you want that, write 2^64-2 to the eventfd and do a
>
> pfd.fd = ...
> pfd.events = POLLOUT;
> poll(&pfd, 1, -1);
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> after the write.
>
> With this algorithm, a write will fail with EINVAL if there is already
> another pending write somewhere. The "poll" will still work after the
> failed write.
Oops, EAGAIN...
Paolo