docs/arm: Document where Xen should be loaded in memory

In commit 9d267c0 ("xen/arm64: Rework the memory layout"), we decided to require Xen to be loaded below 2 TiB to simplify the logic to enable the MMU. The limit was decided based on how known platform boot plus some slack. We had a recent report that this is not sufficient on the AVA platform with a old firmware [1]. But the restriction is not going to change in Xen 4.18. So document the limit clearly in docs/misc/arm/booting.txt. [1] https://lore.kernel.org/[email protected] Signed-off-by: Julien Grall <[email protected]> Reviewed-by: Michal Orzel <[email protected]> Reviewed-by: Bertrand Marquis <[email protected]> Release-acked-by: Henry Wang <[email protected]>
andyhhp · Oct 25, 2023 · 5415b2b · 5415b2b
1 parent d9f07b0
commit 5415b2b
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/docs/misc/arm/booting.txt b/docs/misc/arm/booting.txt
@@ -21,7 +21,9 @@ The exceptions to this on 32-bit ARM are as follows:
  zImage protocol should still be used and not the stricter "raw
  (non-zImage)" protocol described in arm/Booting.
 
-There are no exception on 64-bit ARM.
+The exceptions to this on 64-bit ARM are as follows:
+
+ Xen binary should be loaded in memory below 2 TiB.
 
 Booting Guests
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