[PATCH v9 2/3] PCI: Add a macro to set default alignment for all PCI devices

[Michael Ellerman]

Bjorn Helgaas <helgaas at kernel.org> writes:
>
> I don't know how powerpc kernels are built: can you build a kernel
> that will run on PowerNV as well as on different powerpc systems?

Yes you can. But there are some restrictions.

You can only build a 64-bit OR a 32-bit kernel.

And within 64-bit you can only build a *kernel* for the "server
architecture (~= IBM CPUs)" or the "embedded architecture
(Freescale/NXP)".

So in practice you can build a 64-bit kernel that supports:
 - powernv (bare metal on IBM server chips)
 - pseries (virtualised on IBM server chips or qemu)
 - powermac (Apple G5s)
 - pasemi (long dead but still used by some Amiga folks?)
 - Cell/PS3 (also long dead)

> If so, is it acceptable to force that kernel to user 64K alignment even
> when it's running on non-PowerNV systems?

Probably, but I'm not sure TBH. Benh will know, I'll try and get his
attention.

cheers