In article <200210101507.g9AF7wD15075@pc960.cambridge.arm.com>
rearnsha@arm.com wrote:

> True, but the other issue (24-bit address space) would mean that I'd 
> expect on average for 7/8ths of the buffers to be outside the addressable 
> range (I've got 128 Mb of ram).  Yet the failures, though there are far 
> less common than that.

"Out of addressable range" would be handled by bounce buffer,
and the real problem is whether the DMA address for bus-master devices
is physical address (like on i386) or not.

I guess only isadma by 8237 DMA controllers works
(higher address may be handled by the chipset?),
but all bus-master devices on ISA would have trouble.
---
Izumi Tsutsui
tsutsui@ceres.dti.ne.jp