kern.maxdsiz on amd63 with i386 binaries

Joe Marcus Clarke marcus at
Sat Oct 25 15:53:53 PDT 2008

Chris Peterson wrote:
> Thanks Joe, that did it.
> Out of curiosity, I don't see any of the compat tree in
> /boot/defaults/loader.conf, is there any place this is documented
> besides kernel sources? If not then I guess I should give something back
> to the community and change that :)

Not that I found.  I typically find stuff like this by running sysctl -a
and grepping for familiar patterns.


> Regards,
> Chris Peterson
> On Oct 24, 2008, at 9:03 PM, Joe Marcus Clarke wrote:
>> Chris Peterson wrote:
>>> Hello,
>>> I've got a handful of i386 boxes, and a handful of amd64 boxes running a
>>> 32-bit application, the reasons for this exact configuration mystify me
>>> as well as the deployment predates my time in the environment. Now that
>>> the dataset the application is loading is rapidly approaching 512MB
>>> we're starting to tweak kern.maxdsiz and kern.dfldsiz to 1GB.
>>> The i386 boxes are doing great, but we hit an issue with the amd64
>>> machines in that 64bit apps seem to work fine, but the 32bit apps
>>> running on the amd64 machines fail to be able to use more than the i386
>>> default of 512MB no matter what we set kern.maxdsiz to. I've also tried
>>> compiling it into the kernel, which results in the same issue.
>>> I tried starting the app with "limits -d 1090519040", and it seems to
>>> fail as well. Limits does show the proper value for datasize of
>>> 1064960 kB.
>>> We're locked into 32-bit binaries for this app at the moment thanks to
>>> some uh... interesting libraries it uses, so the usual option of
>>> recompile isn't available. I'd like to avoid traveling from San Jose to
>>> Seattle, then Virginia, then Munich to reinstall the amd64 machines with
>>> i386 machines if at all possible.
>>> Uh... help?
>> Have you tried setting compat.ia32.maxdsiz?  I believe this will do what
>> you want.
>> Joe
>> -- 
>> Joe Marcus Clarke
>> FreeBSD GNOME Team    ::    gnome at
>> FreeNode / #freebsd-gnome
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Joe Marcus Clarke
FreeBSD GNOME Team	::	gnome at
FreeNode / #freebsd-gnome

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