On Wed, Jun 15, 2016 at 10:25:10AM +0100, Mark Rutland wrote: > On Tue, Jun 14, 2016 at 08:16:08PM +0200, Alexander Potapenko wrote: > > On Tue, Jun 14, 2016 at 7:55 PM, Mark Rutland <[email protected]> wrote: > > > I built and booted (via EFI) a kernel with this feature enabled (also > > > with the boot/Makefile change removed). I haven't tested the feature > > > itself as such, as I'm not sure how to do that. > > You can test it by running the test program from Documentation/kcov.txt. > > Ah, I hadn't spotted that. If I get the chance I'll try to give that a > go.
I just had a go (with this applied atop of v4.7-rc3), and I get: root@ribbensteg:/home/nanook# ./kcov mmap: No such device The device exists (it was able to open the fd, evidently): root@ribbensteg:/home/nanook# ls -al /sys/kernel/debug/kcov -rw------- 1 root root 0 Jan 1 1970 /sys/kernel/debug/kcov Strace show me: openat(AT_FDCWD, "/sys/kernel/debug/kcov", O_RDWR) = 3 ioctl(3, CHIOMOVE or CM_IOCGATR, 0x10000) = 0 mmap(NULL, 524288, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = -1 ENODEV (No such device) It doesn't look like the error paths in kcov_mmap are hitting. Any ideas? Thanks, Mark.
