Re: [PATCH] Introduce compat_u64 and compat_s64 types

[Matthew Wilcox <matthew@wil.cx>]

On Sat, Jun 16, 2007 at 12:34:11PM +0100, David Woodhouse wrote:
> You're right. My question was probably not relevant -- all these 64-bit
> architectures cope with misaligned loads anyway. If we ever have to deal
> with 32-bit compat on a 64-bit architecture which can't handle
> misalignment, I'm just going to hide under my desk and never come out.

... 32-bit compat on a 64-bit architecture where the 32-bit architecture
aligned 64-bit quantities to 32-bit boundaries ...

> > On x86_64, misaligned loads are always ok, so gcc never needs to
> > care about this, even attribute((packed)) does not cause byte access
> > here.
> 
> IA64 too, but it'll be handled there too -- either naturally or by
> fixups; it doesn't matter.

Yes.  iirc, McKinley and later handle misaligned loads within a cacheline
without interrupting.  Merced would interrupt on every misaligned load.