Re: [PATCH v4 35/45] linux-user/aarch64: Add SM bit to SVE signal context

[Richard Henderson]

On 7/4/22 17:32, Peter Maydell wrote:
> > @@ -177,9 +180,13 @@ static void target_setup_sve_record(struct 
> > target_sve_context *sve,
> >   {
> >       int i, j;
> >
> > +    memset(sve, 0, sizeof(*sve));
> >       __put_user(TARGET_SVE_MAGIC, &sve->head.magic);
> >       __put_user(size, &sve->head.size);
> >       __put_user(vq * TARGET_SVE_VQ_BYTES, &sve->vl);
> > +    if (FIELD_EX64(env->svcr, SVCR, SM)) {
> > +        __put_user(TARGET_SVE_SIG_FLAG_SM, &sve->flags);
> > +    }
>
> The kernel documentation says that if this is set then the SVE
> record contains the streaming vector length. Does that happen
> automatically (ie vq is the right thing for both streaming
> and non-streaming) or do we need to do something there?

It is automatically correct (modulo the typo you found in patch 40).  The two helpers we 
have are for VL and SVL, with no direct access to NVL.

> I gather that the other half of handling this bit (allowing
> it to be changed on signal-return) is in a later patch.

Yes.


r~