Messages in this thread | | | Subject | Re: Bug: Latest (rc2 and beyond) kernel fails on Dreamcast | From | Adrian McMenamin <> | Date | Tue, 20 Jan 2009 21:20:21 +0000 |
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On Tue, 2009-01-20 at 20:40 +0000, Adrian McMenamin wrote: > 2009/1/20 Paul Mundt <lethal@linux-sh.org>: > > On Mon, Jan 19, 2009 at 10:33:57PM +0000, Adrian McMenamin wrote: > >> 2009/1/19 Adrian McMenamin <lkmladrian@gmail.com>: > >> > 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@cmpxchg.org> > >> Date: Tue Jan 6 14:43:10 2009 -0800 > >> > >> dma-coherent: catch oversized requests to dma_alloc_from_coherent() > >> > > > > > > > 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? > > > > Hmmm... > > >From printks I stuck in the code > > [ 3.641267] Size is 0x1800, mem->size is 0x8 > [ 3.644996] Size is 0x2810, mem->size is 0x8 > > The sizes are correct - the first is the TX buffer, the second RX, but > I have no idea why mem->size is set so low, I assume that is a bug > somewhere else in the Dreamcast code. Any clues gratefully received. > --
Actually, it looks to me that the patch was wrong.
This is from kernel/dma-coherent.c
dev->dma_mem->size = pages;
Yet this is the test applied in dma_alloc_from_coherent:
if (unlikely(size > mem->size))
Should surely be:
if (unlikely (size > (mem->size >> PAGE_SHIFT)))
Will patch that and try it
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