Subject: Re: Badness in dma_alloc_init

From: Kalle Pokki <[email-masked]>
Date: Mon, 09 Jan 2006 15:35:20 +0200

Aristeu Sergio Rozanski Filho wrote:

>Hi!
>  
>
>>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?
>>    
>>
>probably your IMAP_ADDR is at 0xff000000, isn't it? if it is, please adjust
>CONFIG_CONSISTENT_START to an address like 0xe0000000.
>
>  
>
True, my IMAP_ADDR is at 0xff000000. But IMAP_SIZE is just 64 KB, so 
there should be no overlap, right? Or is the IMAP memory area mapped 
with an 8-MB TLB entry or something like that?

No badness in dma-mapping.c anymore with CONFIG_CONSISTENT_START being 
0xe0000000, however. Thanks.