[PATCH v2 01/20] target/arm: Add commentary for CPUARMState.exclusive_high

[Richard Henderson <richard.henderson@linaro.org>]

Document the meaning of exclusive_high in a big-endian context,
and why we can't change it now.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index d469a2637b..4e16eab82e 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -677,8 +677,15 @@ typedef struct CPUArchState {
         uint64_t zcr_el[4];   /* ZCR_EL[1-3] */
         uint64_t smcr_el[4];  /* SMCR_EL[1-3] */
     } vfp;
+
     uint64_t exclusive_addr;
     uint64_t exclusive_val;
+    /*
+     * Contains the 'val' for the second 64-bit register of LDXP, which comes
+     * from the higher address, not the high part of a complete 128-bit value.
+     * This is perhaps confusingly named, but the name is now baked into the
+     * migration format.
+     */
     uint64_t exclusive_high;
 
     /* iwMMXt coprocessor state.  */
-- 
2.34.1