This field may be used to describe the precise atomicity requirements
of the guest, which may then be used to constrain the methods by which
it may be emulated by the host.
For instance, the AArch64 LDP (32-bit) instruction changes semantics
with ARMv8.4 LSE2, from
MO_64 | MO_ATOM_IFALIGN_PAIR
(64-bits, single-copy atomic only on 4 byte units,
nonatomic if not aligned by 4),
to
MO_64 | MO_ATOM_WITHIN16
(64-bits, single-copy atomic within a 16 byte block)
The former may be implemented with two 4 byte loads, or a single 8 byte
load if that happens to be efficient on the host. The latter may not
be implemented with two 4 byte loads and may also require a helper when
misaligned.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Replace a config-time define with a compile time condition
define (compatible with clang and gcc) that must be declared prior to
its usage. This avoids having a global configure time define, but also
prevents from bad usage, if the config header wasn't included before.
This can help to make some code independent from qemu too.
gcc supports __BYTE_ORDER__ from about 4.6 and clang from 3.2.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
[ For the s390x parts I'm involved in ]
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220323155743.1585078-7-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We have lacked expressive support for memory sizes larger
than 64-bits for a while. Fixing that requires adjustment
to several points where we used this for array indexing,
and two places that develop -Wswitch warnings after the change.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
