Re: Synchronization [was Re: The Magic Show: kernel_map() disappearing]
From: Benjamin Herrenschmidt <hidden>
Date: 1999-01-14 13:27:52
On Thu, Jan 14, 1999, Jesper Skov [off-list ref] wrote:
We would want to use eieio for drivers and such accessing their controller in a strict serialized manner. We would want to use sync for SMP related stuff since it ensures, well, synchronization between multiple CPUs wrt memory access.
And I'll add the usual warning: If the device is a PCI device and you
need to make sure that the write actually reached the device (for example
making sure the interrupt enable bits are set before re-enabling the
interrupts on the CPU), you should add a read from the same device (from
the same bus should be enough) to make sure tall the bridges in the path
to the device completed their write.
Remember that a write to PCI is usually a "posted write" and so is
asynchronous, regardless of eieio or sync's done on the CPU.
--
E-Mail: <mailto:bh40@calva.net>
BenH. Web : <http://calvaweb.calvacom.fr/bh40/>
[[ This message was sent via the linuxppc-dev mailing list. Replies are ]]
[[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]]
[[ reply is of general interest. To unsubscribe from linuxppc-dev, send ]]
[[ the message 'unsubscribe' to linuxppc-dev-request@lists.linuxppc.org ]]