Re: [PATCH v3 2/2] tests/ide-test: Create a single unit-test covering more PRDT cases

[Kevin Wolf <kwolf@redhat.com>]

Am 07.01.2020 um 23:39 hat Alexander Popov geschrieben:
> > Did you have a look why this happens? I suppose we might be running out
> > of some resources in the qtest framework becasue each send_dma_request()
> > calls get_pci_device() again?
> 
> I've spent some time on investigating, but didn't succeed.
> 
> 1. After several hundreds of send_dma_request() calls the following assertion in
> that function fails:
>     assert_bit_clear(qpci_io_readb(dev, ide_bar, reg_status), BSY | DRQ);
> 
> 2. If I comment out this assertion, the test system proceeds but eventually stalls.
> 
> 3. I tried to send the CMD_FLUSH_CACHE command to the device, it didn't help.
> 
> 4. That behavior is not influenced by ide_dma_cb() code that I changed.
> 
> I guess it would be better if that effect is examined by somebody with more
> knowledge about DMA and qtest.
> 
> > 5 seconds isn't that bad, so this shouldn't block this series, but it's
> > still by far the slowest test in ide-test, so any improvement certainly
> > wouldn't hurt.
> 
> Thanks for not making that mandatory. It would take me much more time.

Ok, don't bother then.

I seem to remember that I ran into something similar some time ago and
found out that it was related to some integer overflow, I think during
the PCI BAR mapping. This might be the same. Maybe I'll have another
look later.

Kevin