Re: Latest brk patchset

From: Jeremy Fitzhardinge
Date: Sun Mar 15 2009 - 02:03:50 EST


H. Peter Anvin wrote:
On this subject, what is the point of the 64 K "slop space", and if it
is necessary, why not just put it as a RESERVE_BRK() somewhere (*with* a
significant comment as to its necessity) instead of putting it as a
hack in the linker script?

Specifically, its to deal with space taken by alignment constraints. At least some of the extend_brk() calls are page aligned, so that uses up to another 4k. There are other ways to deal with it (pass an alignment to RESERVE_BRK and have it add it into the total, or just assume the user knows to include alignment overheads), but it seemed more straightforward to add some padding in the linker script. After all, anything unused will get freed. (But, yes, it could probably be documented as such, and 64k is a somewhat arbitrary number.)

J
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