target/arm: Add sve-default-vector-length cpu property
Mirror the behavour of /proc/sys/abi/sve_default_vector_length
under the real linux kernel. We have no way of passing along
a real default across exec like the kernel can, but this is a
decent way of adjusting the startup vector length of a process.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/482
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20210723203344.968563-4-richard.henderson@linaro.org
[PMM: tweaked docs formatting, document -1 special-case,
added fixup patch from RTH mentioning QEMU's maximum veclen.]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index be9a4dc..9f0a5f8 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1006,6 +1006,11 @@
/* Used to set the maximum vector length the cpu will support. */
uint32_t sve_max_vq;
+#ifdef CONFIG_USER_ONLY
+ /* Used to set the default vector length at process start. */
+ uint32_t sve_default_vq;
+#endif
+
/*
* In sve_vq_map each set bit is a supported vector length of
* (bit-number + 1) * 16 bytes, i.e. each bit number + 1 is the vector
