target/arm: Add commentary for CPUARMState.exclusive_high

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

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230530191438.411344-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2023-06-06 10:19:34 +01:00 committed by Peter Maydell
parent 8d7f954a7f
commit 0f08429c46

View File

@ -677,8 +677,16 @@ 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.
* In some ways it might be more convenient to record the exclusive value
* as the low and high halves of a 128 bit data value, but the current
* semantics of these fields are baked into the migration format.
*/
uint64_t exclusive_high;
/* iwMMXt coprocessor state. */