I would like to use the 64 bit version of OpenBSD, but I'm not really sure how good it works.

Are there any known problems? Is the 32 bit version more recommended for productive environment?


I assume that you're wondering about amd64 vs i386, the 64-bit and 32-bit architectures on PCs (there's also a choice of word size on Sparc64).

According to the official platform description:

The only major shortcoming at this time is that the kernel debugger ddb is somewhat poor.

Another mentioned limitation is that if your processor lacks the NX bit (most amd64 processors have it), on a 64-bit system, you won't get OpenBSD's protection against some exploits based on uploading executable code as data and exploiting a bug (e.g. a buffer overflow) to execute that code.

Another resource to check is the FAQ. Most importantly, unlike on many other operating systems, you can't run 32-bit binaries on OpenBSD/amd64.

There are several virtualization technologies that allow running OpenBSD/amd64 and OpenBSD/i386 on the same machine (Xen, Vmware, and VirtualBox should support OpenBSD/amd64 guests with a 64-bit hypervisor or host OS; I don't know if there's a way to virtualize OpenBSD/i386 on an OpenBSD/amd64 host).

  • Should be brought up that OpenBSD does not do multilib. So if you do go with amd64 keep in mind running any 32bit binaries is probably out of the question. – gregf Nov 19 '10 at 22:31
  • @gregf: It's worse than just not multilib: as I indicate in my answer, according to the FAQ, an amd64 OpenBSD kernel can't run an i386 OpenBSD binary. – Gilles 'SO- stop being evil' Nov 19 '10 at 22:52
  • Is this a security feature, the lack of compatibility-mode support in the OpenBSD kernel? – Michael Trausch Dec 16 '10 at 21:26
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    @Michael: I think it's just about simplicity. Of course, simplicity is good for security (for example, if you support both, you need 32bit↔64bit gateways all over the place, which are as many opportunities for an omitted or botched range check). – Gilles 'SO- stop being evil' Dec 16 '10 at 21:39

I have used 64bit OpenBSD as a firewall and router without problems for over 2 years, and would highly recomend its stability.


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