Hello, > * Mark E Mason <mark.e.mason@xxxxxxxxxxxx> [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 > platform. 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). Thanks, Mark > -- > Martin Michlmayr > http://www.cyrius.com/ > >
