Re: Memory Write Ordering Question

[Alan Cox]

> I'm wondering if anyone has any idea what exactly is causing this.  The
> readl is a so-so work around.  I'd like to figure out how to do it
> correctly.  Does anyone who knows more about Intel CPU's and write
> ordering and PCI have any ideas?

Its entirely a PCI issue. PCI writes are posted and may be deferred. However
a write cannot pass another write to the device, nor a read, so your read
is the real solution.

The full horror is in the PCI specs which you can get on CD nowdays fairly
sanely. Basically PCI is a message passing system disguised as a bus, treat
it as the former and you wont get too badly hurt