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== Articles == | == Links == |
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* [[https://github.com/kilobyte/crossgrade|crossgrade script by kilobyte]] * [[SummerOfCode2020/UnApprovedProjects/ArchitectureCrossGrade|GSoC 2020 crossgrading project]] |
Contents
Cross-grading a Debian System
This page is meant to document the procedure for cross-grading a Debian install using Multiarch.
Pre-requisites
The first Debian release to feature Multiarch is Wheezy, so you will need to upgrade before attempting the procedure described here.
A full backup is also strongly recommended as this procedure is still very much work in progress. Reinstalling is still the safer option. You have been warned!
Steps
These are the steps for converting an i386 install to amd64, but they should be applicable for any other architecture pairs if your machine can run both (e.g. armel and armhf). You can use arch-test to determine which Debian architectures your system can run. You can install qemu-user-static add support for more Debian architectures.
Add the new architecture
# dpkg --print-architecture i386 # dpkg --add-architecture amd64 # dpkg --print-foreign-architectures amd64 # apt update
Install a kernel that supports both architectures in userland
# apt install linux-image-amd64:amd64 # reboot
Make sure you are actually running the new kernel before proceeding with the next steps (uname -a).
Make sure all packages are in sync between architectures
You need to upgrade first, or otherwise check all the versions of packages to be crossgraded in this step, to make sure all amd64/i386 packages are in version-sync, otherwise the cross-grade will break.
# apt clean # apt upgrade
Crossgrade `dpkg` `tar` and `apt`
Get all the packages needed to replace dpkg, tar and apt, then install them for the new architecture. It is changing dpkg that actually 'counts' for changing the default arch. Tar has to be replaced with dpkg, not apt otherwise it gets removed then there is no tar to put the new one back with.
# apt --download-only install dpkg:amd64 tar:amd64 apt:amd64 # dpkg --install /var/cache/apt/archives/*_amd64.deb # dpkg --print-architecture amd64 # dpkg --print-foreign-architectures i386 # apt update # apt upgrade # apt full-upgrade
Crossgrade all other architecture-dependent packages
If you got this far you are now effectively running amd64, but with mostly i386 packages. You can try to replace them with the corresponding amd64 packages. If that doesn't work (not all libraries will necessarily have been converted to Multiarch yet) it should be possible to remove the i386 package and install the amd64 version instead.
Before a mass replacement from old to new architectures, if you have packages without installation candidates (from old releases), you may want to first try removing those with
# apt install aptitude:amd64 # aptitude purge '?obsolete'
A possible brute-force way to do the swap is
# apt install $(dpkg -l | grep '^.i.*:i386' | grep :i386 | sed -e s/:i386/:amd64/ | awk '{print $2}')
You will have to type in 'Yes, do as I say' to get apt to do this, so make sure each package in the warning is actually going to get installed with the new architecture.
Another more brutal way to do the swap is
# dpkg --get-selections | grep '\binstall$' | grep :i386 | sed -e s/:i386/:amd64/ | dpkg --set-selections # apt -f install
You will have to type in 'Yes, do as I say' to get apt to do this.
Once the swap is done, you can remove all the redundant libraries and drop the old architecture with
# apt purge $(dpkg -l | grep '^.i.*:i386' | awk '{print $2}') # dpkg --remove-architecture i386 # apt update
Caveats and Known Problems
Caution with systemd
systemd may not like being cross-graded, possibly it is safer to cross-grade it from a liveCD. Make sure to cross-grade udev at the same time, otherwise various units will fail.
APT dependency resolver wants to revert apt itself
If the system had packages that depend on apt like apt-utils, it's possible run into a situation where apt -f install wants to revert apt itself to i386. Aborting and doing another operation apt autoremove will illustrate the reason better:
The following packages have unmet dependencies: apt-utils:i386 : Depends: apt:i386 (= 1.4.8) but it is not installed
In such a case, the solution is to temporarily remove apt-utils:i386 from the system, and install apt-utils afterwards. Note: this new apt-utils will be amd64, but once you switch apt to amd64, using the :amd64 suffix will not work.
Apt dependency resolver generates broken solutions
It might happen that apt's resolver emits an unworkable solution:
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. E: Unable to correct dependencies
In this case you can inspect what packages are marked as Broken and decide what to do:
# apt -o Debug::pkgProblemResolver=1 -f install
KDE
The KDE desktop environment creates the file ~/.config/Trolltech.conf which contains locations of shared libararies and, more problematic, their architecture. This causes panel widgets to crash. The file can apparently be safely removed or renamed to fix these problems.
iamerican (and possibly others/similar)
Similar to KDE, some package(s) (e.g. iamerican on at least Debian 7.5) may have saved caches/hashes that need updating. E.g. encountered:
$ echo foo | spell /usr/bin/ispell: Illegal format hash table $
corrected with:
# (cd / && umask 022 && dpkg-reconfigure iamerican)
which then caused updating of: /var/lib/ispell/american.hash
Links
Announce by Guillem Jover, dpkg Maintainer (see "Cross-grading" at the bottom of the message)
Howto amd64 an i386 Debian installation with multiarch by Marc Haber
Crossgrading Debian in 2017 by Simon Richter
Upgrading Debian from 32-bit to 64-bit - AKA crossgrading from i386 to amd64 by anarcat
i386 to amd64 - Debian 7.5 from i386 to amd64, discussion + links to edited script(1) capture, etc., by Michael Paoli
- Articles by Jose M. Calhariz:
?GSoC 2020 crossgrading project
Sample cross-grade script
Here is a script to essentially do the above for you. It could do with some work to put in a lot more error checking, but it works OK on a build-essential basic chroot - you may have problems on a more fully-configured real system. Use at your own risk!
# scary script to crossgrade your debian machine between arches. # usage crossgrade <final-architecture> set -e if [ -z "$1" ]; then echo "Usage: crossgrade <architecture> (debian architecture to convert to)" exit 1 fi #validate arch if ! TO=$(dpkg-architecture -qDEB_HOST_ARCH -a$1); then echo "$1 is not a recognised architecture name" exit 1 fi FROM=$(dpkg --print-architecture) echo "Crossgrading from $FROM to $TO" #check for a compatible kernel # should check $FROM and $TO harder # allow for switching kernel over too to minimal one if requested? case $TO in amd64) TO_KERN=amd64 ;; i386) TO_KERN=amd64 ;; armhf) TO_KERN=armhf ;; armel) TO_KERN=armhf ;; arm64) TO_KERN=arm64 ;; mips) TO_KERN=mips64le ;; mipsel) TO_KERN=mips64le ;; mips64le) TO_KERN=mips64le ;; ppc) TO_KERN=ppc64el ;; powerpc) TO_KERN=ppc64el ;; ppc64el) TO_KERN=ppc64el esac dpkg --add-architecture $TO # check that dpkg --print-foreign-architectures is $TO apt update apt upgrade # Install a kernel capable to run the new architecture with the old # architecture in userspace KERNEL=$(uname -m) echo "Current kernel arch is $KERNEL" if [ "$KERNEL" != "$TO_KERN" ]; then if apt install linux-image-$TO:$TO; then echo "There should be a reboot here" exit 1 #reboot else echo "kernel updating to linux-image-$TO:$TO failed" fi fi echo Crossgrading dpkg and apt apt clean apt --download-only install dpkg:$TO apt:$TO tar:$TO #check ever package to be installed is available in same version for amd64 if installed (multiarch sync is needed) #for pkg in /var/cache/apt/archives/*_$TO.deb #do # file=$(basename $pkg) # pkgname= ${file%%_.*} # version= ${file##*._} # if dpkg -l $($pkgname) #done #in practice this needs to run twice (do it more? is there a better way?) if ! dpkg --install /var/cache/apt/archives/*_$TO.deb; then dpkg --install /var/cache/apt/archives/*_$TO.deb fi test $(dpkg --print-architecture) = $TO test $(dpkg --print-foreign-architectures | grep $FROM) = $FROM echo "Yay! dpkg and apt crossgrade completed successfully" echo "Updating core packages" apt upgrade apt full-upgrade echo "Removing obsolete packages" apt install aptitude:$TO aptitude purge '?obsolete' echo "Mass reinstalling $TO packages -- double check installed packages match warned-about packages" apt install $(dpkg -l | grep '^.i.*:'"$FROM" | grep ":$FROM" | sed -e "s/:$FROM/:$TO/" | awk '{print $2}') echo "Removing redundant libraries" apt purge $(dpkg -l | grep '^.i.*:'"$FROM" | awk '{print $2}') echo "Removing $FROM" dpkg --remove-architecture "$FROM" apt update