On 11/24/20 15:50, Will Deacon wrote: > Allow systems with mismatched 32-bit support at EL0 to run 32-bit > applications based on a new kernel parameter. > > Signed-off-by: Will Deacon <will@xxxxxxxxxx> > --- > Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ > arch/arm64/kernel/cpufeature.c | 7 +++++++ > 2 files changed, 14 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 526d65d8573a..f20188c44d83 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -289,6 +289,13 @@ > do not want to use tracing_snapshot_alloc() as it needs > to be done where GFP_KERNEL allocations are allowed. > > + allow_mismatched_32bit_el0 [ARM64] > + Allow execve() of 32-bit applications and setting of the > + PER_LINUX32 personality on systems where only a strict > + subset of the CPUs support 32-bit EL0. When this > + parameter is present, the set of CPUs supporting 32-bit > + EL0 is indicated by /sys/devices/system/cpu/aarch32_el0. Shouldn't we document that a randomly selected 32-bit CPU will be prevented from being hotplugged out all the time to act as the last man standing for any currently running 32-bit application. That was a mouthful! I'm sure you can phrase it better :-) If we make this the last patch as it was before adding affinity handling, we can drop patch 4 more easily I think? Thanks -- Qais Yousef
