On Tue, Jan 26, 2021 at 04:15:37PM +0100, Peter Zijlstra wrote: > On Tue, Jan 26, 2021 at 08:51:55AM -0600, Josh Poimboeuf wrote: > > User space mixes compiler versions all the time. The C ABI is stable. > > > > What specifically is the harder issue you're referring to? > > I don't think the C ABI captures nearly enough. Imagine trying to mix a > compiler with and without asm-goto support (ok, we fail to build without > by now, but just imagine). > > No C ABI violated, but having that GCC extention vs not having it > radically changes the kernel ABI. > > I think I'm with Greg here, just don't do it. Ok, thank you for an actual example. asm goto is a good one. But it's not a cut-and-dry issue. Otherwise how could modversions possibly work? So yes, we should enforce GCC versions, but I still haven't seen a reason it should be more than just "same compiler and *major* version". -- Josh
