On Tue, Mar 15, 2011 at 01:00:04PM +0100, Marcin Juszkiewicz wrote: > Some time ago I looked at cross toolchain packages to find how they > handle installation of several versions at same time. It was done by > using 'update-alternatives' tool and was broken. We fixed it during > Ubuntu/Maverick cycle but "u-a" is still in use (just versions are used > now to take care of priority so latest gcc is default one). > But this is different then native gcc which is selected by gcc-defaults > package - /usr/bin/gcc is symlink to /usr/bin/gcc-DEFAULTVERSION (where > DEFAULTVERSION value depends on architecture and distribution). Ok, we > have gcc-defaults-armel-cross in Ubuntu but it takes care only of > depending on default versions of cross toolchain components. > I filled a bug [1] about it and discussed it with Matthias Klose. The > proper way would consists those steps: > - new cross packages will use "u-a remove" to get rid of old alternative > stuff (in postinst and prerm) > - new gcc-defaults-armel-cross package will provide > /usr/bin/arm-linux-gnueabi-APP symlinks > - new gcc-defaults-armel-cross will also conflicts with older versions > of cross toolchain packages From the bug report: 4. alter postinst/prerm of gcc-4.[45]-armel-cross to remove old u-a: TODO This should be done in the preinst instead. Rationale: update-alternatives is part of dpkg, so doesn't require any Pre-Depends; and a dependency (such as the gcc-arm-linux-gnueabi dependency on gcc-4.5-arm-linux-gnueabi) does not prevent one package from being unpacked before the postinst of another package it depends on has been run. So if you do this in the postinst, you get: - gcc-4.5-arm-linux-gnueabi unpacked (enforced by the Conflicts: from gcc-arm-linux-gnueabi) - gcc-arm-linux-gnueabi unpacked; overwrites /usr/bin/arm-linux-gnueabi-gcc symlink - gcc-4.5-arm-linux-gnueabi configured; u-a remove runs, removing the symlink - gcc-arm-linux-gnueabi configured - but the gcc symlink is now missing Otherwise, this looks ok. -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ slangasek@ubuntu.com vorlon@debian.org
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