On Wed, Mar 3, 2021 at 8:27 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > On Mon, Jan 25, 2021 at 02:42:10PM -0600, Josh Poimboeuf wrote: > > When building out-of-tree kernel modules, the build system doesn't > > require the GCC version to match the version used to build the original > > kernel. That's probably [1] fine. > > > > In fact, for many distros, the version of GCC used to build the latest > > kernel doesn't necessarily match the latest released GCC, so a GCC > > mismatch turns out to be pretty common. And with CONFIG_MODVERSIONS > > it's probably more common. > > > > So a lot of users have come to rely on being able to use a different > > version of GCC when building OOT modules. > > > > But with GCC plugins enabled, that's no longer allowed: > > > > cc1: error: incompatible gcc/plugin versions > > cc1: error: failed to initialize plugin ./scripts/gcc-plugins/structleak_plugin.so > > > > That error comes from the plugin's call to > > plugin_default_version_check(), which strictly enforces the GCC version. > > The strict check makes sense, because there's nothing to prevent the GCC > > plugin ABI from changing -- and it often does. > > > > But failing the build isn't necessary. For most plugins, OOT modules > > will otherwise work just fine without the plugin instrumentation. > > > > When a GCC version mismatch is detected, print a warning and disable the > > plugin. The only exception is the RANDSTRUCT plugin which needs all > > code to see the same struct layouts. In that case print an error. > > Hi Masahiro, > > This problem is becoming more prevalent. We will need to fix it one way > or another, if we want to support distro adoption of these GCC > plugin-based features. > > Frank suggested a possibly better idea: always rebuild the plugins when > the GCC version changes. That is just another form of the previous patch, which was already rejected. - That is a hack just for external modules - Our consensus is, use the same version for the kernel and external modules I use Ubuntu, and I do not see such a problem. (I have never seen it on Debian either, except sid.) I see Fedora providing GCC whose version is different from the one used for building the kernel. That is a problem on the distribution side. In my ubuntu. $ grep CC_VERSION_TEXT /lib/modules/$(uname -r)/build/.config CONFIG_CC_VERSION_TEXT="gcc (Ubuntu 10.2.0-13ubuntu1) 10.2.0" $ gcc --version | head -n1 gcc (Ubuntu 10.2.0-13ubuntu1) 10.2.0 > What do you think? NACK. > Any suggestions on how to > implement that? Otherwise I can try to hack something together. > > -- > Josh > -- Best Regards Masahiro Yamada
