On Mon, May 18, 2020 at 12:26:30PM +0100, Vladimir Murzin wrote: > On 5/15/20 6:16 PM, Catalin Marinas wrote: > > For performance analysis it may be desirable to disable MTE altogether > > via an early param. Introduce arm64.mte_disable and, if true, filter out > > the sanitised ID_AA64PFR1_EL1.MTE field to avoid exposing the HWCAP to > > user. > > > > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> > > Cc: Will Deacon <will@xxxxxxxxxx> > > --- > > > > Notes: > > New in v4. > > > > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > > arch/arm64/kernel/cpufeature.c | 11 +++++++++++ > > 2 files changed, 15 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index f2a93c8679e8..7436e7462b85 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -373,6 +373,10 @@ > > arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards > > Format: <io>,<irq>,<nodeID> > > > > + arm64.mte_disable= > > + [ARM64] Disable Linux support for the Memory > > + Tagging Extension (both user and in-kernel). > > + > > Should it really to take parameter (on/off/true/false)? It may lead to expectation > that arm64.mte_disable=false should enable MT and, yes, double negatives make it > look ugly, so if we do need parameter, can it be arm64.mte=on/off/true/false? I don't think "performance analysis" is a good justification for this parameter tbh. We don't tend to add these options for other architectural features, and I don't see why MTE is any different in this regard. Will
