Re: Bug: Latest (rc2 and beyond) kernel fails on Dreamcast

[Paul Mundt]

On Mon, Jan 19, 2009 at 10:33:57PM +0000, Adrian McMenamin wrote:
> 2009/1/19 Adrian McMenamin <lkmladrian@xxxxxxxxx>:
> > I haven't had time to look at this, but the most up to date kernel
> > (and the one of around a week ago also) fails to boot, seemingly
> > seeking an IP address for the 8139too based NIC.
> 
> > [    4.664236] Sending DHCP requests .<3>eth0: PCI Bus error 2200.
> > [    4.669582] eth0: PCI Bus error 2200.
> 
> And the bisection reveals the following:
> 
> adrian@bossclass:~/linux-2.6$ git bisect bad
> 58c6d3dfe436eb8cfb451981d8fdc9044eaf42da is first bad commit
> commit 58c6d3dfe436eb8cfb451981d8fdc9044eaf42da
> Author: Johannes Weiner <hannes@xxxxxxxxxxx>
> Date:   Tue Jan 6 14:43:10 2009 -0800
> 
>     dma-coherent: catch oversized requests to dma_alloc_from_coherent()
> 
>     Prevent passing an order to bitmap_find_free_region() that is larger than
>     the actual bitmap can represent.
> 
>     These requests can come from device drivers that have no idea how big the
>     dma region is and need to rely on dma_alloc_from_coherent() to sort it out
>     for them.
> 
>     Reported-by: Guennadi Liakhovetski <lg@xxxxxxx>
>     Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
>     Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
>     Cc: Dmitry Baryshkov <dbaryshkov@xxxxxxxxx>
>     Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
>     Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> 
> :040000 040000 5c8a694b778f36a3254103d99cb73b561cb84565
> 5efd4e32eb145f32ca4e96aefbea08f4f8f4d27d M	kernel

The dreamcast uses a 32kB coherent area for PCI DMA, which all of the
8139too allocations should fit under just fine. What does
dma_alloc_from_coherent() say the requested size is, vs the per-device
memory size for each allocation?
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