Review request for 5049299

[Andrew Haley]

Florian Weimer wrote:
> * Andrew Haley:
> 
>> However, I think you don't want PROT_NONE whan a system has been configured
>> with mode 2: in that case, a user has a reasonable expectation that
>> they can use all of the memory they allocated at VM startup.  It makes
>> more sense to allocate all the -Xms size immediately.
> 
> -Xms?  Or -Xmx?

-Xms as a minimum: the user has a entitlement to that.  It's not unreasonable
that later heap expansion might fail.

> The latter leads to problems if the maximum heap size is relatively large.
> Currently, -Xmx is reserved, and some software fails to build on
> vm.overcommit_memory systems due to this.

I don't get it.  Why would overcommit cause some software to fail to
build?  I can understand it failing if overcommit was turned off.

Andrew.