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Date: Mon, 09 Jan 2006 14:31:03 +0200
From: Kalle Pokki <kalle.pokki@iki.fi>
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To: linuxppc-embedded <linuxppc-embedded@ozlabs.org>
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Subject: Badness in dma_alloc_init
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Hi all,

I'm having some trouble with the DMA allocation using Linux 2.6.14-rc2 + 
some platform modifications. Namely, the dma_alloc_coherent() function 
returns bogus virtual addresses causing machine check exceptions. At 
boot, the kernel complains there is something wrong, but I cannot figure 
out how to fix it. CONFIG_CONSISTENT_START is at its default value, 
0xff100000. Any hints where to look further?

Oh, this is a custom 8xx board. Has the support for DMA in 8xx been 
unstable at the time of pre-2.6.14?

Linux version 2.6.14-rc2 (kp@host32.eke.fi) (gcc version 4.0.0 (DENX 
ELDK 4.0 4.
0.0)) #1 Mon Jan 9 12:53:41 EET 2006
Built 1 zonelists
Kernel command line: root=/dev/mtdblock1 ro console=ttyCPM0,115200
PID hash table entries: 256 (order: 8, 4096 bytes)
Decrementer Frequency = 247500000/60
Console: colour dummy device 80x25
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 30268k available (1608k kernel code, 376k data, 100k init, 0k 
highmem)
Mount-cache hash table entries: 512
Badness in dma_alloc_init at arch/ppc/kernel/dma-mapping.c:348
Call trace: [c0003670]  [c0003f24]  [c0003320]  [c01e2ad0]  [c000228c]  
[c000551
c]

... followed by otherwise good startup.