[openib-general] [PATCH v2 1/7] IB/core - Add DMA mapping functions to allow device drivers to interpose

[Ralph Campbell]

>  > Although the driver compiles on 32-bit kernels, it is unsupported
>  > and never been tested. All known 64-bit systems don't define
>  > CONFIG_HIGHMEM.  In spite of previous emails suggesting that
>  > page_address() can return NULL without CONFIG_HIGHMEM defined,
>  > the code in include/linux/mm.h doesn't allow it (assuming the
>  > page pointer is valid and not some random address).
>  > I verified this with Andrew Morton.
>
> Hmm, is there no way to make this work on 32-bit kernels?  I don't
> want to do something that we'll have to change again if we want to
> make things work on 32-bits.
>
> (And I know that qlogic has no intention of supporting the driver on
> 32-bit kernels, but we shouldn't make it impossible for someone else
> to fix it)

I don't think this is impossible to implement.  I just wanted
to avoid the work unless you and others thought it was really
worth it given the reality that we already have a large
test matrix of platforms, distros, and kernel versions and
it probably won't get much testing.  It is possible that
at some point 32-bit kernels will become a priority
but I don't know when that might happen.