Re: [Qemu-devel] SeaBIOS regression

[John Snow]

On 2/5/19 4:47 AM, Thomas Huth wrote:
> On 2019-02-05 10:42, Gerd Hoffmann wrote:
>> On Tue, Feb 05, 2019 at 10:31:24AM +0100, Thomas Huth wrote:
>>> On 2019-02-05 08:52, Gerd Hoffmann wrote:
>>>> On Mon, Feb 04, 2019 at 04:10:37PM +0100, Thomas Huth wrote:
>>>>>
>>>>>  Hi Gerd,
>>>>>
>>>>> I noticed that certain FreeDOS images are not working correctly anymore
>>>>> with the current version of QEMU, for example
>>>>> http://www.qemu-advent-calendar.org/2016/download/day10.tar.xz ... It
>>>>> aborts with:
>>>>>
>>>>>  Error reading from drive C: DOS area: write-protection violation 
>>>>> attempted
>>>>>
>>>>> I've bisected the issue, and it has apparently been introduced with:
>>>>>
>>>>>  cd1bfd5ef336166b275a09dc9842542bf5e63ae3
>>>>>  seabios: update bios and vgabios binaries
>>>>>
>>>>> Any idea what might be going wrong here?
>>>>
>>>> Hmm, no.  bisect seabios?
>>>
>>> I haven't bisected yet, but it seems to be related to CONFIG_ATA_DMA=y
>>> in our roms/config.seabios-128k config file. When I switch that to "n",
>>> then the old FreeDOS disks are working again...
>>
>> Hmm, guess I should turn that off again on the next update (there will
>> be a seabios 1.12.1 release before qemu 4.0).
> 
> Ah, right, I just noticed that this has just been enabled in QEMU for
> the 3.0 release, where the problem occurred for the first time. So this
> switch is likely the culprit, not a change in SeaBIOS. I'd also vote to
> revert commit eda553a442e94d now.
> 
>  Thomas
> 

If you enable the tracing in hw/ide/core, does it say anything that
looks interesting? I'm wondering if there's some deficiency there.