PAE, i686 vs. x86_64 (was: Recommendations)

Michael ODonnell michael.odonnell at comcast.net
Wed Jun 16 11:50:10 EDT 2010



> 32-bit apps run fine in a 64-bit Linux OS, and in many cases better
> since the OS can manage memory a bit more efficiently.  The downside
> is that you need to install the required 32-bit libraries too.
> So far, I have not seen a 32-bit application that could not run on
> a 64-bit Linux OS.  They are still running native, but they think
> they are running in a 32-bit OS even though the drivers themselves
> may be 64-bit drivers.

Right.  We were in the midst of (what we thought was) an orderly
transition from a rather dated i686 distro to a more current i686
distro targetted at the same hardware and didn't realize until
late in the game that support for 4Gb user space had gone away.
We had to scramble to instead migrate to an x86_64 distro,
obliging some of our customers to upgrade their hardware earlier
than anticipated.  Since even just porting the apps/libs forward
to the newer GCC tools was already proving painful we chose not
to convert them to 64bit entities and, as you say, native kernel
support for 32bit entities in the x86_64 kernels has proven to
be solid.  It was quite the adventure, though, and there was
wailing and gnashing of teeth as we had expected the new distro
to be (more or less) a drop-in replacement for the old one...



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