Re: [Qemu-devel] [PATCH v3 10/16] s390-bios: Support for running format-0/1 channel programs

[Cornelia Huck]

On Thu, 7 Mar 2019 14:25:00 -0500
"Jason J. Herne" <address@hidden> wrote:

> On 3/4/19 1:25 PM, Cornelia Huck wrote:
> > On Fri,  1 Mar 2019 13:59:30 -0500
> > "Jason J. Herne" <address@hidden> wrote:

> >> +    consume_io_int();
> >> +
> >> +    /* collect status */
> >> +    rc = tsch(schid, irb);
> >> +    if (rc) {
> >> +        print_int("tsch failed with rc=", rc);
> >> +    }  
> > 
> > Hm. The whole code flow relies on the fact that not only no more than
> > one cpu is enabled for I/O interrupts, but also only one subchannel.
> > Otherwise, you could get an interrupt for another subchannel, which
> > would be the only way you'd get cc 1 on the tsch for this subchannel
> > here (no status pending). Maybe peek at the interruption information
> > stored into the lowcore first?
> > 
> > Won't be a problem with the code as it is now, though, AFAICS.
> >   
> Agreed, voting to leave as is. Perhaps a comment to explain that we rely on 
> only one 
> "Active" i/o device?

Yes, sounds good.