We have a ppc32 MPC8248 board that is working perfectly with the 4.19
kernel.
We have noticed two issues with the 5.2 kernel:
1) If the new CONFIG_PPC_KUAP (kernel userspace access protection) is
enabled the kernel freezes right after initializing all the drivers and
just before starting /sbin/init.
2) If CONFIG_PPC_KUAP is disabled the system starts up, but any user space
program will hang indefinitely after calling the GCC atomic
"__sync_bool_compare_and_swap". This happens when nginx starts. The same
nginx binary works fine on a 4.19 kernel.
Hi Doug,
Le 26/07/2019 à 00:30, Doug Crawford a écrit :
We have a ppc32 MPC8248 board that is working perfectly with the 4.19 kernel.
We have noticed two issues with the 5.2 kernel:
Have you tried 5.0 and 5.1 ?
1) If the new CONFIG_PPC_KUAP (kernel userspace access protection) is enabled the kernel freezes right after initializing all the drivers and just before starting /sbin/init.
Can you provide your .config ?
Can you also provide the output of the boot console ?
2) If CONFIG_PPC_KUAP is disabled the system starts up, but any user space program will hang indefinitely after calling the GCC atomic "__sync_bool_compare_and_swap". This happens when nginx starts. The same nginx binary works fine on a 4.19 kernel.
Can you provide 'dmesg' ?
What version of GCC do you use ?
Have you tried a simple program doing nothing else than __sync_bool_compare_and_swap() ?
Can you provide a disassembly of the function that uses __sync_bool_compare_and_swap() ?
Thanks
Christophe