Messages in this thread | | | Date | Thu, 13 Dec 2001 18:02:56 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: Repost: could ia32 mmap() allocations grow downward? |
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On Thu, 13 Dec 2001, Wayne Whitney wrote: > On Thu, 13 Dec 2001, Hugh Dickins wrote: > > > My fear is that you may encounter an indefinite number of buggy apps, > > which expect an mmap() to follow the mmap() before: easy bug to > > commit, and to go unnoticed, until you reverse the layout. > > Hmm, so which is more important to support, buggy users of (unguaranteed > side effects of) the new interface, or users of the legacy interface? I > can see the argument that that the buggy users of the new interface are > more important. Maybe CONFIG_MMAP_GROWS_DOWNWARDS, or a /proc entry?
Hard to know until you try it: my fear may prove groundless, or experience may discourage you from the exercise completely.
Quick guess is that what you'd really want in the end is not a CONFIG option or /proc tunable, but some mark in an ELF section for what behaviour that particular executable wants.
I'm reluctant to call wanting a large virtual address space buggy; but expecting contiguous ascending mmaps (without MAP_FIXED) is buggy.
Hugh
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