On Wed, Nov 01 2006, Mike Miller (OS Dev) wrote:
>
> PATCH 5/8
>
> This disables DMA prefetch for the P600 on IPF. A chip bug may result in
> a DMA prefetch going falling off into holes in memory. On Proliant x86[_64]
> systems the top page of memory is mapped out and the io hole below 4GB is
> similiarly protected because the memory at the lower boundary of the hole
> is used by ACPI and other things.
> Please consider this for inclusion.
>
> Thanks,
> mikem
>
> Signed-off-by: Mike Miller <mike.miller@xxxxxx>
>
> cciss.c | 14 ++++++++++++++
> cciss_cmd.h | 1 +
> 2 files changed, 15 insertions(+)
> --------------------------------------------------------------------------------
> diff -urNp linux-2.6-p00004/drivers/block/cciss.c linux-2.6/drivers/block/cciss.c
> --- linux-2.6-p00004/drivers/block/cciss.c 2006-10-31 15:20:25.000000000 -0600
> +++ linux-2.6/drivers/block/cciss.c 2006-10-31 15:42:59.000000000 -0600
> @@ -2997,6 +2997,20 @@ static int cciss_pci_init(ctlr_info_t *c
> }
> #endif
>
> +#ifdef CONFIG_IA64
> + {
> + /* DMA prefetch must be disabled on P600 on platforms that may
> + * present noncontiguous memory.
> + */
> + __u32 dma_prefetch
> + if(board_id == 0x3225103C) {
> + dma_prefetch = readl(c->vaddr + I2O_DMA1_CFG);
> + dma_prefetch |= 0x8000;
> + writel(dma_prefetch, c->vaddr + I2O_DMA1_CFG);
> + }
> + }
> +#endif /* CONFIG_IA64 */
Hmm, what about other platforms with discontig memory support?
--
Jens Axboe
-
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