On Tue, Nov 10, 2020 at 08:04:26AM +0100, Greg Kroah-Hartman wrote: > On Mon, Nov 09, 2020 at 09:30:21PM +0000, Will Deacon wrote: > > Since 32-bit applications will be killed if they are caught trying to > > execute on a 64-bit-only CPU in a mismatched system, advertise the set > > of 32-bit capable CPUs to userspace in sysfs. > > > > Signed-off-by: Will Deacon <will@xxxxxxxxxx> > > --- > > .../ABI/testing/sysfs-devices-system-cpu | 9 +++++++++ > > arch/arm64/kernel/cpufeature.c | 19 +++++++++++++++++++ > > 2 files changed, 28 insertions(+) > > I still think the "kill processes that can not run on this CPU" is crazy I agree it's crazy, though we try to keep the kernel support simple while making it a user-space problem. The alternative is to force-migrate such process to a more capable CPU, potentially against the desired user cpumask. In addition, we'd have to block CPU hot-unplug in case the last 32-bit capable CPU disappears. The only sane thing is not to allow 32-bit processes at all on such hardware but I think we lost that battle ;). -- Catalin
