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From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <07abf6bb-ec21-da2c-bc8c-c9f136ba5c01@redhat.com>
Date: Tue, 29 Nov 2016 17:13:27 +0100
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Subject: Re: [Qemu-devel] Linux kernel polling for QEMU
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To: Andrew Jones <drjones@redhat.com>, Fam Zheng <famz@redhat.com>
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Jens Axboe <axboe@fb.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Davide Libenzi <davidel@xmailserver.org>, Christoph Hellwig <hch@lst.de>



On 29/11/2016 17:01, Andrew Jones wrote:
> OK, it may be due to scheduling then. Below is the test case (for AArch64)
> Also, I forgot to mention before that I can only see this with TCG, not
> KVM. If ppoll is allowed to timeout, then the test will complete. If not,
> then, as can be seen with strace, the iothread is stuck in ppoll, and the
> test never completes.
> 
>  #include <asm/smp.h>
>  volatile int ready;
>  void set_ready(void) {
>      ready = 1;
>      while(1);
>  }
>  int main(void) {
>      smp_boot_secondary(1, set_ready);
>      while (!ready);
>      return 0;
>  }

Where is the test stuck?

Paolo