From: Andrea Arcangeli Date: Wed, 2 Apr 2008 07:06:44 +0000 (+0200) Subject: Fix bounce setting for 64-bit X-Git-Tag: v2.6.25-rc9~101^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=00d61e3e8c12d5f395b167856d2b3c430816afb0;p=linux-2.6 Fix bounce setting for 64-bit Looking a bit closer into this regression the reason this can't be right is that dma_addr common default is BLK_BOUNCE_HIGH and most machines have less than 4G. So if you do: if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) dma = 1 that will translate to: if (BLK_BOUNCE_HIGH <= BLK_BOUNCE_HIGH) dma = 1 So for 99% of hardware this will trigger unnecessary GFP_DMA allocations and isa pooling operations. Also note how the 32bit code still does b_pfn < blk_max_low_pfn. I guess this is what you were looking after. I didn't verify but as far as I can tell, this will stop the regression with isa dma operations at boot for 99% of blkdev/memory combinations out there and I guess this fixes the setups with >4G of ram and 32bit pci cards as well (this also retains symmetry with the 32bit code). Signed-off-by: Andrea Arcangeli Signed-off-by: Jens Axboe --- diff --git a/block/blk-settings.c b/block/blk-settings.c index 1344a0ea5c..5713f7e5cb 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -140,7 +140,7 @@ void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) /* Assume anything <= 4GB can be handled by IOMMU. Actually some IOMMUs can handle everything, but I don't know of a way to test this here. */ - if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) + if (b_pfn < (min_t(u64, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) dma = 1; q->bounce_pfn = max_low_pfn; #else