Re: [discuss] Re: x86_64: 2.6.14-rc4 swiotlb broken

[Ravikiran G Thirumalai <kiran@scalex86.org>]

On Tue, Oct 18, 2005 at 03:28:27PM -0600, Alex Williamson wrote:
> ... 
>    Oops, I used 2.6.14-rc4-mm1, I'll retest.  However, this does work on
> the Superdome.  Not because of the iterating over the nodes code, but
> because of the call to alloc_bootmem_low_pages() fallback case.  Adding
> a printk(), I get this:
> 
> Node 0: 0xe000074104e6b200
> Node 1: 0xe000082080723000
> Node 2: 0xe000000101532000  *Note this is the interleaved memory node
> Placing software IO TLB between 0x4cdc000 - 0x8cdc000
> 
> Looking at the memory map of the system, I see these major ranges:
> 
> Node 2:
> 0x00000000000 - 0x0007ffdefff (~2GB)
> 0x00100000000 - 0x0017fffffff (2GB)
> 0x04080000000 - 0x040f0000000 (2GB)
> Node 0:
> 0x74100000000 - 0x741fbbfffff (~4GB)
> Node 1:
> 0x82080000000 - 0x820fb453fff (~2GB)
> 
> So, it looks like we're iterating over the nodes, but
> alloc_bootmem_node() isn't even guaranteed to try to get memory from the
> low memory on that node.

Thanks Alex. 2.6.14-rc4-mm1 already has the 
guarantee-dma-area-for-alloc_bootmem_low.patch by Yasunori-san.  So it is 
safer to confirm results on latest 2.6.14 stock.

Could it also be that Node 2 is offline when swiotlb is allocated?

Thanks,
Kiran