svn commit: r344487 - in head/sys: conf gnu/gcov

[Alan Somers]

It's not a problem with the version; they're built from the same
source.  But is there a problem with the compiler?  Can a GCC-built
kernel work with Clang-built world?

On Tue, Mar 5, 2019 at 12:54 AM Matthew Macy <mmacy at freebsd.org> wrote:
>
> World? It looks like there's a version mismatch between the kernel and modules.
>
> -M
>
> On Thu, Feb 28, 2019 at 7:11 PM Alan Somers <asomers at freebsd.org> wrote:
> >
> > On Thu, Feb 28, 2019 at 6:40 PM Matthew Macy <mmacy at freebsd.org> wrote:
> > >
> > > to config add:
> > > options LINDEBUGFS
> > > options GCOV
> > >
> > > compile kernel with gcc (otherwise it will be a no-op)
> > >
> > > sysctl debug.gcov.enable=1
> > >
> > > mount -t debugfs debugfs /sys/kernel/debug
> > >
> > > (or wherever) and the output artifacts will appear under gcov/<kernel
> > > build path> - you need to be root to see the artifacts
> > >
> > > gcov can then generate the results as it would normally from the
> > > profiling and the build time artifacts
> > >
> > > bug reports welcome
> > >
> > >
> > > -M
> >
> > Here's a bug report: I rebuilt the kernel but boot fails with this
> > error.  Do I need to rebuild world too?
> >
> > Mounting local filesystems:kldload: fdescfs.ko: lost base for reltab
> > linker_load_file: /boot/kernel/fdescfs.ko - unsupported file type
> > mount: fdescfs: Operation not supported by device
> > Mounting /etc/fstab filesystems failed, will retry after root mount hold release
> > kldload: fdescfs.ko: lost base for reltab
> > linker_load_file: /boot/kernel/fdescfs.ko - unsupported file type
> > mount: fdescfs: Operation not supported by device
> > .
> > Mounting /etc/fstab filesystems failed, startup aborted