64bit x86 kernel ddi_dma_mem_alloc got fail

Question

Hi Dear All,
I had met 64bit x86 sol10 kernel ddi_dma_mem_alloc fail when driver load after system boot.
I had spend much time to research, but When I reboot this system, my scsi driver attach ok and have not got ddi_dma_mem_alloc fail.
It is a tricky thing.
This driver work fine at 32bit x86 sol10kernel,
and have not met this issue.
I only share my "bad" experience.

Answer 1

Not conforming to the requirements of the device may
be more critical than just being non-optimum. The
bind may fail. It will do so, for example, if the
address is not aligned correctly. Your code must be
responsible for making sure the memory does conform to
the requirement, anfd your code better be prepared to
deal with the errors that result if they do not.Thanks, Richard. Clean failure I can live with - my worry was that it might silently do something nasty, like DMAing to the wrong bit of memory. I should hope this very unlikely - it ought to be possible to pass any random address to the bind (by accident, perhaps) and get a clean failure if the address is unsuitable.
Note that you are doing something unusual. When
doing something unusual, you are more likely to run
into cases not anticipated by the DDI designers. You
can never really be sure that your code will work
correctly on combinations of platforms and Solaris
versions that you have not tested.Well understood - I've been on all sides of this sort of situation a few times. In my experience, the architects and high-level designers often have a totally generic approach, but the implementors sometimes only think (and test) in terms of how they expect it to be used normally. Unusual things can look like they ought to work, then get caught out by some implementation detail or bug.
Many thanks for the reply. Do you have any thoughts on my other posting about who is reponsible for looking after alignment and address range limitations with DMA? Your opinion would be welcome.