Re: USB problems after memory upgrade

[David Brownlee <abs%netbsd.org@localhost>]

On 11 September 2011 17:42, Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost> 
wrote:
>> How hard would it be to provide a kernel option to specifically
>> allocate the highest possibly memory locations for devices, to try to
>> flush out such issues?
>
> bus_dmatag_subregion(9) is an API to handle such issue,
> as it was introduced for bce(4) that could not xfer to >1GB RAM.

As I understand it, its possible that there may be similar >2GB, >4GB
etc issues lurking in other drivers, which would only trigger if they
happen to be allocated memory over such a boundary.

I was wondering how hard it would be to have a kernel option which
would force all memory to be allocated from as high an address as
possible, to try to deterministically trigger such issues, so they
could be more easily found and corrected.