Re: new mremap(2): relax alignment restrictions?

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> On Wed, Jul 25, 2007 at 04:51:46PM -0400, der Mouse wrote:

Digging out old mail, are we? :)

>> (I'd actually *prefer* getting SEGV/BUS/etc for accesses to space
>> after EOF [in an mmapped file], but that would be quite run-time
>> expensive to do, and likely somewhat difficult besides.)
> To make that efficient, we'd need flexible *segmentation* on top of
> paging in the hardware - that is, a MMU length field per page with
> byte granularity.

Right.  "Quite run-time expensive" because hardware without that -
which AIUI is most of the machines we run on - would have to protect
the page and simulate all accesses in the kernel.

Actually, on reflection, "quite expensive" doesn't half cover it.
"Execrably slow" might be more like it.

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