Re: [PATCH v5 20/22] tests/tcg/aarch64: add test-sve-ioctl guest-debug test

[Richard Henderson]

On 1/14/20 5:09 AM, Alex Bennée wrote:
> This test exercises the gdbstub while runing the sve-iotcl test. I
> haven't plubmed it into make system as we need a way of verifying if
> gdb has the right support for SVE.
> 
> Signed-off-by: Alex Bennée <address@hidden>
> 
> ---
> v4
>   - interrogate ZCR_EL1 directly as no longer have vg

Note that ZCR_EL1 does not give you the correct answer if the hypervisor has
set ZCR_EL2 to something lower.  Also, ZCR_EL1 it itself not correct if the
hardware does not support all vector sizes.

See some of Andrew Jones' qemu command-line work.  Try -cpu max,sve512=on and
then use the ioctl to set vq to 3 (sve384).  The result will be an effective vq
of 2 (sve256).

We *really* need vg, as computed from sve_zcr_len_for_el().


r~