Re: 2.6.18-rc5-mm1: drivers/infiniband/hw/amso1100/c2.c compile error

Roland Dreier
2006-09-01T17:34:32Z

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.

- R.