Re: x86_64: 2.6.14-rc4 swiotlb broken

[Andrew Morton]

Ravikiran G Thirumalai <kiran@xxxxxxxxxxxx> wrote:
>
> On x86_64 NUMA boxes, the revert
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=6e3254c4e2927c117044a02acf5f5b56e1373053
> meant that swiotlb gets the IOTLB
> memory from pages over 4G (if mem > 4G), which basically renders swiotlb useless, causing
> breakage with devices not capable of DMA beyond 4G.  2.6.13 was (kinda) not
> broken, although the patch titled "Reverse order of bootmem lists" was
> not in 2.6.13, The reason is commit
> http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=6142891a0c0209c91aa4a98f725de0d6e2ed4918
> was not in 2.6.13, PCI_DMA_BUS_IS_PHYS was 1 when no mmu was present, and the block layer did 
> the bouncing, never using swiotlb.  I guess the right fix is to make sure
> swiotlb gets the right memory.  Here is a patch doing that.  Tested on IBM
> x460.  I hope the patch is ok for ia64s too.  I do not have access to ia64
> boxen.
> 

This is an ia64 patch - what point was there in testing it on an x460?

Is something missing here?

>  
> Index: linux-2.6.14-rc4/arch/ia64/lib/swiotlb.c
> ===================================================================
> --- linux-2.6.14-rc4.orig/arch/ia64/lib/swiotlb.c	2005-10-14 00:06:21.000000000 -0700
> +++ linux-2.6.14-rc4/arch/ia64/lib/swiotlb.c	2005-10-17 00:05:22.000000000 -0700
> @@ -123,7 +123,7 @@
>  	/*
>  	 * Get IO TLB memory from the low pages
>  	 */
> -	io_tlb_start = alloc_bootmem_low_pages(io_tlb_nslabs *
> +	io_tlb_start = alloc_bootmem_node(NODE_DATA(0), io_tlb_nslabs *
>  					       (1 << IO_TLB_SHIFT));
>  	if (!io_tlb_start)
>  		panic("Cannot allocate SWIOTLB buffer");
-
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