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* [dpdk-dev] PCI memory sync (kvm,dpdk,e1000,packet stalled)
@ 2019-11-20 14:40 ASM
  2019-11-20 17:36 ` PCI memory sync question " ASM
  0 siblings, 1 reply; 8+ messages in thread
From: ASM @ 2019-11-20 14:40 UTC (permalink / raw)
  To: pbonzini, anthony.perard, dev, tiwei.bie, jianfeng.tan

Hi folks!

I trying solve the problem, with packets stopping (e1000,tap,kvm).
My studies led to the following:
1. From flatview_write_continue() I see, what e1000 writes the number
"7" to the STAT register.
2. The driver from target OS reads STAT register with number "7" and
writes to the register the number "0".
3. From flatview_write_continue() (I make edits):
            memcpy(ptr, buf, l);
            new1=ptr[0xc];
            usleep(100);
            new2=ptr[0xc];
            invalidate_and_set_dirty(mr, addr1, l);
            new3=ptr[0xc];
printf("Old: %i, new1, %i, new2: %i, new3: %i\n", old,new1,new2,new3);

I see what memory in first printf is "7", but after usleep() is "0".
Do I understand correctly that this should not be? Or RCU lock
suggests the ability to the multiple writers?

The problem is that qemu(e1000) writes the number 7, after which
target(dpdk driver) reads 7, on the basis of this it writes the number
0, but as a result (extremely rarely), the value STATUS still remains
7. Therefore, packet processing is interrupted. This behavior is
observed only on kvm (it is not observed on tcg).

Please help with advice or ideas.

P.S. I started a bug report earlier. There is more detailed
information. In my broken English:
bugs.launchpad.net/qemu/+bug/1853123

---
Best regards,
Leonid Myravjev

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2022-05-23 13:01 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-20 14:40 [dpdk-dev] PCI memory sync (kvm,dpdk,e1000,packet stalled) ASM
2019-11-20 17:36 ` PCI memory sync question " ASM
2019-11-21 14:05   ` Stefan Hajnoczi
2019-11-27 12:39     ` ASM
2019-12-19 14:58       ` Stefan Hajnoczi
2019-12-30 10:10         ` ASM
2020-01-02 11:05           ` Stefan Hajnoczi
2022-05-23 12:47             ` Ding Hui

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