From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: To: 9fans@9fans.net From: Richard Miller <9fans@hamnavoe.com> Date: Tue, 9 Feb 2010 15:23:16 +0000 In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] Plan 9 on Xen 3.2.1 / 32-bit PAE Kernel / 64-bit Topicbox-Message-UUID: d12b6ede-ead5-11e9-9d60-3106f5b1d025 > could you explain this a little further. pae would normally > not be useful with 2gb of ram and is often of dubious utility > on a 4gb machine. what's different about xen? PAE is of no utility at all as far as I can see, but sometimes we have to run xen guests on somebody else's hypervisor (think virtual hosting companies). If the hypervisor is configured with PAE (or 64-bit, it seems), the guest has to run in PAE mode. I hacked the Plan 9 xen kernel to support PAE for this reason, but since my xen test machine has only a couple of gigs I have never actually seen it work in the non-trivial case where the upper half of a 64-bit page address is non-zero. If our friend has more than 4GB and the panic disappears when he uses less than 2GB, that might indicate why he's having problems that nobody else has seen.