Bart Smaalders wrote:
> Roland Mainz wrote:
> > Eric Lowe wrote:
> >>>> but there's too much code out there that just breaks.  The
> >>>> programmers made implicit assumptions about the approximate
> >>>> size of a page, and that was that.
> >>> Which code breaks ? Userland or kernel code ? Was
> >> Userland. The problem is that mmap() exposed too much detail
> >> and as a result assumptions about sysconf(_SC_PAGESIZE) or
> >> even the range of possible values resulted in programs dying
> >> when sysconf returns 64K for the pagesize. In other words,
> >> the value of sysconf(_SC_PAGESIZE) has sort of defacto ended>
> >> up baked into the Solaris ABI in an unintentional way.
> >
> > ... but how ? I've read the ABI specs and mmap(2) several times and the
> > only thing which AFAIK may be possible is trouble with MAP_FIXED and
> > rounding. But that's again not in the ABI, it's just that the
> > applications make special assumptions about the page size.
> >
> > I assume this also means a (hypothetical) SPARC CPU which only supports
> > 16k and 256k pages cannot be supported by Solaris, right ?
> 
> Grab a chunk of VA (w/ mmap_noreserve) and then try and
> allocate several pages inside w/ guard pages.  If you
> grabbed a fixed size area initially, your code is broken
> if someone mucks enough w/ the page size.

Do you have any pseudocode around for this ?

----

Bye,
Roland

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