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On Mon, 17 Oct 2005, Jens Axboe wrote: >> how to correct this problem ? > > See your buffer address, it's not aligned. You need to align that as > well. This is needed because the hardware will dma directly to the user > buffer, and to be on the safe side we require the same alignment as the > block layer will normally generate for file system io. > > So in short, just align your read buffer to the same as your block size > and you will be fine. Example: > > #define BS (4096) > #define MASK (BS - 1) > #define ALIGN(buf) (((unsigned long) (buf) + MASK) & ~(MASK)) > > char *ptr = malloc(BS + MASK); > char *buf = (char *) ALIGN(ptr); > > read(fd, buf, BS); Shouldn't one use posix_memalign(3) for that? Grzegorz Kulewski - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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