Re: [Qemu-devel] [PATCH 05/12] S390: ccw firmware: Add main program

[Alexander Graf]

On 04/23/2013 10:58 AM, Cornelia Huck wrote:
> On Mon, 22 Apr 2013 21:18:11 +0200
> Alexander Graf<address@hidden>  wrote:
>
> > This C file is the main driving piece of the s390 ccw firmware. It
> > provides a search for a workable block device, sets it as the default
> > to boot off of and boots from it.
> >
> > Signed-off-by: Alexander Graf<address@hidden>
> > ---
> >   pc-bios/s390-ccw/main.c |   56 +++++++++++++++++++++++++++++++++++++++++++++++
> >   1 files changed, 56 insertions(+), 0 deletions(-)
> >   create mode 100644 pc-bios/s390-ccw/main.c
> >
> > diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
> > new file mode 100644
> > index 0000000..0913aac
> > --- /dev/null
> > +++ b/pc-bios/s390-ccw/main.c
> > @@ -0,0 +1,56 @@
> > +/*
> > + * S390 virtio-ccw loading program
> > + *
> > + * Copyright (c) 2013 Alexander Graf<address@hidden>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> > + * your option) any later version. See the COPYING file in the top-level
> > + * directory.
> > + */
> > +
> > +#include "s390-ccw.h"
> > +
> > +struct subchannel_id blk_schid;
> > +char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
> > +
> > +void virtio_panic(const char *string)
> > +{
> > +    sclp_print(string);
> > +    while (1) { }
> > +}
> > +
> > +static void virtio_setup(void)
> > +{
> > +    struct irb irb;
> > +    int i;
> > +    int r;
> > +    bool found = false;
> > +
> > +    blk_schid.one = 1;
> > +
> > +    for (i = 0; i<  0x10000; i++) {
> > +        blk_schid.sch_no = i;
> > +        r = tsch(blk_schid,&irb);
> You want to do a stsch() loop here, not a tsch() loop :)

What does stsch buy us over tsch?


> As a bonus, you can exit the loop on cc == 3.
>
>             r = stsch(blk_schid,&schib);
>            if (r == 3) {
>               break;
>            }
>
> > +        if (r != 3) {
>             if (schib.pmcw.dnv) {
>
> > +            if (virtio_is_blk(blk_schid)) {
> > +                found = true;
> > +                break;
> > +            }
> > +        }
> > +    }
> > +
> > +    if (!found) {
> > +        virtio_panic("No virtio-blk device found!\n");
> > +    }
> > +
> > +    virtio_setup_block(blk_schid);
> The virtio_is_blk() and virtio_setup_block() functions should go into a
> preceding patch, no?

The code doesn't get compiled before the end of the series anyway, so 
ordering might be slightly off :)


Alex