Jes> Not quite correct as far as I understand it. mmiowb() is
Jes> supposed to guarantee that writes to MMIO space have
Jes> completed before continuing. That of course covers the
Jes> multi-CPU case, but it should also cover the write-combining
Jes> case.
I don't believe this is correct. mmiowb() does not guarantee that
writes have completed -- they may still be pending in a buffer in a
bridge somewhere. The _only_ effect of mmiowb() is to make sure that
writes which have been ordered between CPUs using some other mechanism
(i.e. a lock) are properly ordered by the rest of the system. This
only has an effect systems like very large ia64 systems, where (as I
understand it), writes can pass each other on the way to the PCI bus.
In fact, mmiowb() is a NOP on essentially every architecture.
- R.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
