On Wed, 18 Mar 2026 11:27:04 GMT, Harald Eilertsen <[email protected]> wrote:

>> Thanks @bsdkurt for clarifying. That makes sense. Interesting. OpenBSD is 
>> the first OS I know that includes mmap into RLIMIT_DATA. 
>> 
>> Do you know, by chance, if this also includes "uncommitted" mmapped memory  
>> (as in, allocated with MAP_NORESERVE)? Since we over-allocate quite 
>> drastically with uncommitted memory.
>> 
>> Wait, I see that neither BSD nor MacOS manpages even mention MAP_NORESERVE. 
>> But we use it. Now I am confused :-)
>
>> Wait, I see that neither BSD nor MacOS manpages even mention MAP_NORESERVE. 
>> But we use it. Now I am confused :-)
> 
> We define it to 0 if undefined:
> https://github.com/battleblow/jdk/blob/bsd-port/src/hotspot/os/bsd/os_bsd.cpp#L160
> 
> MAP_NORESERVE does not seem to be defined by Posix. We could perhaps use 
> MAP_NOSYNC on FreeBSD, if I get this right. I don't see anything similar for 
> OpenBSD, however.

Looks like `MAP_NORESERVE` was removed from FreeBSD ages ago...
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193961 (commit 
https://svnweb.freebsd.org/ports?view=revision&revision=374392)

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PR Review Comment: 
https://git.openjdk.org/bsd-port/pull/4#discussion_r2952916143

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