Messages in this thread | | | Subject | Re: TASK_UNMAPPED_BASE & stack location | From | Andi Kleen <> | Date | Sat, 26 Apr 2003 00:58:17 +0200 |
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"Martin J. Bligh" <mbligh@aracnet.com> writes:
>>> Is there any good reason we can't remove TASK_UNMAPPED_BASE, and just >>> shove libraries directly above the program text? Red Hat seems to have >>> patches to dynamically tune it on a per-processes basis anyway ... >> >> Yes. You won't get a continuous sbrk/brk heap then anymore. Not sure it >> is a big problem though. > > Me no understand. I think this *makes* it a contiguous space. The way I see > it, we currently allocate from TASK_UNMAPPED_BASE up to the top, then start > again above program text. Which seems a bit silly.
The space for brk is not completely continuous anymore, especially when you use mmap() too.
Same with mmap.
Basically mmap() and brk/sbrk (=malloc) will fragment each other.
wli's suggestion of making it a personality makes sense.
> I've moved PAGE_OFFSET around a lot (which moves the stack, as you say). > Haven't seen it break anything yet ... IMHO it was broken anyway if this > hurts it. Obviously not something one could do in a stable kernel series, > but 2.5 seems like a perfect time for it to me ... unless I'm missing some > glibc / linker thing, it seems like a simple change.
It at least broke Sun Java.
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