On 16.07.2025 23:23, Volodymyr Babchuk wrote: > By default GCC uses "simple" coverage counter update > mechanism. It is perfectly fine for single-threaded (or single CPU in > our case) setups, but will cause race conditions on SMP systems. > > For example, I observed that counters are going backwards when running > Xen inside QEMU. > > GCC starting from version 7 and LLVM/Clang starting from version 11 > support -fprofile-update=atomic option, which forces coverage counter > updates to be atomic, which resolves the issue. As Xen runs mostly on > SMP systems, force use this option if it is supported by a compiler. > > Signed-off-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
Acked-by: Jan Beulich <jbeul...@suse.com>
