Re: TASK_UNMAPPED_BASE & stack location

Andi Kleen
2003-04-25T21:42:54Z

"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.

But apparently Solaris/x86 is doing that.

It's probably worth a sysctl at least.

> Moreover, can we put the stack back where it's meant to be, below the
> program text, in that wasted 128MB of virtual space? Who really wants
>> 128MB of stack anyway (and can't fix their app)?

You could, but I bet it would break some programs
(e.g. just moving __PAGE_OFFSET on amd64 to 4GB for 32bit broke some things)

-Andi