Date: Sat, 11 Feb 2012 00:02:07 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Randy Bush <randy@psg.com> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: 9-stable from i386 to amd64 Message-ID: <20120211060207.GK5775@dan.emsphone.com> In-Reply-To: <m2y5sa7yt0.wl%randy@psg.com> References: <m2y5sa7yt0.wl%randy@psg.com>
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In the last episode (Feb 10), Randy Bush said: > is there a recipe for moving from i386 to amd64? > > on a very remote system, i made the migration from 7.4 to 8.2 to 9.0, all > 32-bit. it was done with repeated > > make buildworld > make kernel.new [0] > nextboot -k kernel.new > reboot > make installworld > etc > > [0] - well, there were some mv(1)s in there :) > > so after it was happy with 9.0 i386, i went to move to amd64 with > > make buildworld TARGET=amd64 > make kernel TARGET=amd64 DESTDIR=kernel.new [0] > nextboot -k kernel.new > reboot > > it did not come back from the reboot, and required a manual reset. i have > no console access to the machine, not my choice. > > clue bat please. You probably got bit by a mismatched /libexec/ld-elf.so. The kernel expects that to be the "native" version, and on a 64-bit kernel it also expects a ld-elf32.so to be the "compat" 32-bit version. When you rebooted onto the 64-bit kernel, it couldn't find /libexec/ld-elf32.so to run any of the 32-bit binaries on the system. My guess is that your reboot attempt died in /sbin/init, prompting for a path to /bin/sh. If you compiled with a static /bin/sh for performance, it probably died very early in /etc/rc. I think copying ld-elf.so over to ld-elf32.so might have been all you needed to boot, but that would end up with a 64-bit kernel running a true 32-bit userland with all the libraries in the "wrong" place, and your "installworld" step would replace them with their 64-bit equivalents and your install would die halfway through, leaving you with a large mess to clean up. The cleanest upgrade path is to prepare your 32-bit root to be bootable by both 32- and 64-bit kernels: copy the ld-elf32.so that was built during your buildworld over to /libexec/ld-elf32.so, and also make copies of /lib and /usr/lib to /lib32 and /usr/lib32 respectively. That way when you reboot to a 64-bit kernel, your 32-bit executables will be running "correctly" out of compat32 paths and your installworld should succeed. When I did all this on a local system, I made judicious use of ZFS snapshots and clones, preserving a bootable clone of my original system plus intermediate versions all the way until I was happy with the result. I've never done it completely remotely, but if you do a trial run or two on a local machine or VM, you should be able to it confidently remotely. -- Dan Nelson dnelson@allantgroup.com
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