> * Mark E Mason <firstname.lastname@example.org> [2006-03-14 08:21]:
> > There's a lot of PCI HW out there that's 32-bit only, but
> there's also
> > a fair bit that isn't. A 32-bit device in a 64-bit system
> is going to
> > require bounce buffering by the driver/OS.
> If I understand you correctly, you're saying that you
> currently don't supporting 32 bit PCI cards on the SB1
Um - not exactly. A 32-bit device in a 64-bit system will require some
form of bounce buffering. This is true regardless of what the platform
is, or what the OS/RTOS is.
Sun did some interesting stuff with this in the early UltraSPARC systems
with a 'reverse I/O MMU' which bypassed the need for bounce buffering
but imposed other requirements on the drivers and OS. Of course, that
required specialized HW which doesn't seem to be in vogue.
> Is this something you care about, or should I get
> a 64-bit PCI card instead? How hard would it be to implement
> bounce buffering anyway?
This is something I care about.
How difficult it is under Linux - I (personally) don't know. Based on
other posts, it sounds like Linux has a system for it... But like I said
earlier, I'm far more familiar with certain other RTOS/firmware
environments than I am Linux.
If someone more familiar with this area could point me in the right
direction though, I'll get someone to look at it (if I don't myself).
> Martin Michlmayr