Messages in this thread | | | Date | Thu, 18 Oct 2012 10:59:56 +0100 | From | Alan Cox <> | Subject | Re: [PATCH 2/2] staging: et131x: Fix 64bit tx dma address handling |
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> > + skb_headlen(skb), > > + DMA_TO_DEVICE); > > + desc[frag].addr_lo = dma_addr & 0xFFFFFFFF; > > + desc[frag].addr_hi = dma_addr >> 32; > > Maybe use macros defined in kernel.h instead: > > desc[frag].addr_lo = lower_32_bits(dma_addr); > desc[frag].addr_hi = upper_32_bits(dma_addr); > > A few more instances below.
This is actually important because >> 32 of a 32bit value is undefined in C. The compiler is free to do what it likes with this. While the results are usually sane some architectures do generate the equivalent of
x >> (n % wordsize);
Alan
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