[openib-general] [PATCH 2.6.19 2/4] ehca: hcp_phyp.c: correct page mapping in 64k page mode

[Christoph Raisch]

> Umm, so is this patch really needed?  Where did the patch come from --
> is it needed to fix something actually seen, or was it written just
> based on some theoretical understanding?
>
> I'm confused...
>
>  - R.
The patch is needed. We've seen it on the real system. We did fix it on the
real system.
...and it conforms to theory... although theory is a bit confusing here.

let me try to summarize:
ioremap checks for 64k boundary (actually page boundary)
nopage does H_ENTER in 4k granularity if it's configured like that for a
certain type of POWER processor.

so you have to adjust the ioremap to page boundary, and THEN access at the
offset within the 64k.

Took quite a while until we understood that code path.... ;-)

Christoph R.