Comment 6 for bug 1681439

On 04/12/2017 03:51 AM, Michał Kępień wrote:

> $ tail -20 qemu.log
>
> == ide_cancel_dma_sync ==
>
> ATA Registers:
> cmd 0x06
> feature 0x01
> error 0x00
> nsector 0x00000001
> sector 0x00
> lcyl 0x00
> hcyl 0x00
> hob_feature 0x00
> hob_nsector 0x00
> hob_sector 0x00
> hob_lcyl 0x00
> hob_hcyl 0x00
> select 0x60
> status 0x58
> lba48 0x00000000
> qemu-system-x86_64: hw/ide/core.c:704: ide_cancel_dma_sync: Assertion `s->bus->dma->aiocb == NULL' failed.
> $ grep ^cmd qemu.log | sort | uniq -c
> 128 cmd 0x06
> 151854 cmd 0xc8
> 217496 cmd 0xca
>
> I am happy to help if any further debugging is required.
>

Whoops, I misunderstood exactly how often cancel would be invoked here,
sorry about that. It looks like when DMA is finished and the guest
signals that it's over, we cancel any outstanding DMA just to be safe,
and that'd explain the nearly 400,000 calls in your logs.

However, this looks like it might legitimately be trying to cancel a
TRIM command (I don't know why ...) but we don't clean up after those
properly.

Let's try and see if this doesn't fix your problem:
https://github.com/jnsnow/qemu/commit/57bf2ccdfe8dd35838c1e6642bf9bd76dc9ad1a9

Optionally, you can delete the printf from the last patch if you want.
I'm still a little concerned that your guest is trying to cancel
in-flight commands which I didn't think would happen under normal
circumstances unless some other problem arose, but I think this will
clear up the assert for us.

Thanks,
-John