Messages in this thread | | | Subject | Re: 2.6.18-rc5-mm1: drivers/infiniband/hw/amso1100/c2.c compile error | From | Roland Dreier <> | Date | Fri, 01 Sep 2006 10:34:24 -0700 |
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Andrew> What's __raw_writeq() supposed to do, anyway? On alpha Andrew> it's writeq() without an mb(). On parisc it's writeq() Andrew> only the data is byte-reversed. On sparc64() it's Andrew> incomprehensible. On everything else it's writeq().
My understanding is that __raw_writeq() is like writeq() except not strongly ordered and without the byte-swap on big-endian architectures. The __raw_writeX() variants are convenient to avoid having to write inefficient code like writel(swab32(foo), ...) when talking to a PCI device that wants big-endian data. Without the raw variant, you end up with a double swap on big-endian architectures.
sparc64 looks wrong, since __raw_writeq() seems identical to writeq(), which seems to imply it's going to swab what is stores.
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