Re: [Qemu-devel] [Qemu-ppc] macio ide question/bug report

[Mark Cave-Ayland]

On 15/05/14 21:28, BALATON Zoltan wrote:

> On Thu, 15 May 2014, BALATON Zoltan wrote:
> > On Thu, 15 May 2014, BALATON Zoltan wrote:
> > > confusing.) Do you think that replacing io->len in your patch with
> > > s->io_buffer_size would be the correct thing to do?

That looks reasonable, as the MIN() will help prevent excessive memory 
clobber.

> > Probably that's not enough. I've tried it and then it gets to here:
>
> I should've also included these lines too to make it more clear what did
> I change:

Yes, this is definitely helpful. It appears that cmd_read_toc_pma_atip() 
returns 0x20 bytes of data (can you confirm this?), while the DMA engine 
is configured to transfer 0x324 bytes of data - perhaps this is the 
maximum possible size of a TOC?. So the existing code determines there 
are still 0x324 - 0x20 = 0x304 bytes remaining for the DMA request and 
falls into the unaligned code which is definitely not what we want.

Perhaps we need to assume for a non-IO DMA request that the result will 
only be a single ATAPI reply packet? Attached is another version of the 
patch for you to experiment with which makes your s->io_buffer_size 
change but also moves the logic into pmac_ide_transfer() so that we 
don't inadvertently drop into the unaligned code.


ATB,

Mark.

qemu-macio-atapi-v2.patch
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