Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64

BATCHED_UNMAP_TLB_FLUSH is used on x86 to do batched tlb shootdown by
sending one IPI to TLB flush all entries after unmapping pages rather
than sending an IPI to flush each individual entry.
On arm64, tlb shootdown is done by hardware. Flush instructions are
innershareable. The local flushes are limited to the boot (1 per CPU)
and when a task is getting a new ASID.
So marking this feature as "TODO" is not proper. ".." isn't good as
well. So this patch adds a "N/A" for this kind of features which are
not needed on some architectures.

Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210223003230.11976-1-song.bao.hua@hisilicon.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/features/arch-support.txt b/Documentation/features/arch-support.txt
index d22a1095e661c0578c76fd94131e5fe50855a691..118ae031840b7e5a9a42d920cbe1dcaae0defb29 100644 (file)
--- a/Documentation/features/arch-support.txt
+++ b/Documentation/features/arch-support.txt
@@ -8,4 +8,5 @@ The meaning of entries in the tables is:
     | ok |  # feature supported by the architecture
     |TODO|  # feature not yet supported by the architecture
     | .. |  # feature cannot be supported by the hardware
+    | N/A|  # feature doesn't apply to the architecture
 

diff --git a/Documentation/features/vm/TLB/arch-support.txt b/Documentation/features/vm/TLB/arch-support.txt
index 48a5ca54839935e4f7721824de4358491cf738e2..e1c3a4c4d107a8afa4c2318d7a3be02ffbad826f 100644 (file)
--- a/Documentation/features/vm/TLB/arch-support.txt
+++ b/Documentation/features/vm/TLB/arch-support.txt
@@ -9,7 +9,7 @@
     |       alpha: | TODO |
     |         arc: | TODO |
     |         arm: | TODO |
-    |       arm64: | TODO |
+    |       arm64: | N/A  |
     |        csky: | TODO |
     |       h8300: |  ..  |
     |     hexagon: | TODO |