[Jamvm-general] /hg/release/icedtea6-1.10: JamVM: Base default min and max heap ...

[Xerxes Ranby]

On 2011-03-24 17:22, Xerxes Rånby wrote:
> Hi the IcedTea buildbot found a multiplication overflow bug in the new
> default min max heap size on physical memory calculation code when running JamVM on a system with a lot of RAM.
>
> http://git.berlios.de/cgi-bin/cgit.cgi/jamvm/commit/?id=cc6997003dd65ba5a32df471b7c0547fba9769f2
> http://builder.classpath.org/icedtea/buildbot/builders/icedtea6-jaunty-ia32-quick-jamvm/builds/35
>
> JamVM fails to launch on the icedtea buildbot with 3.6G of RAM
Attached patch fix.

The multiplication of num_pages*pages_size caused a long sign flip 
overflow. Then later when the sign flipped long got divided by 4 and 
converted back to unsigned form caused the calculated min-heap argument 
to end up in the 4Gb range.

Cheers and have a great day!
Xerxes


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