Re: [Qemu-devel] [PATCH v3 13/16] s390-bios: Use control unit type to determine boot method

[Cornelia Huck <cohuck@redhat.com>]

On Fri,  1 Mar 2019 13:59:33 -0500
"Jason J. Herne" <jjherne@linux.ibm.com> wrote:

> The boot method is different depending on which device type we are
> booting from. Let's examine the control unit type to determine if we're
> a virtio device. We'll eventually add a case to check for a real dasd device
> here as well.
> 
> Since we have to call enable_subchannel() in main now, might as well
> remove that call from virtio.c : run_ccw().

Any reason you cannot add the enable_subchannel() in the previous
patch? Then you never need to introduce it in run_ccw() :)

> 
> Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
> ---
>  pc-bios/s390-ccw/main.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
> index 0670c14..ed79b7a 100644
> --- a/pc-bios/s390-ccw/main.c
> +++ b/pc-bios/s390-ccw/main.c
> @@ -198,13 +198,24 @@ static void virtio_setup(void)
>  
>  int main(void)
>  {
> +    uint16_t cutype;
> +
>      sclp_setup();
>      css_setup();
>      boot_setup();
>      find_boot_device();
> +    enable_subchannel(blk_schid);
>  
> -    virtio_setup();
> -    zipl_load(); /* no return */
> +    cutype = cu_type(blk_schid);
> +    switch (cutype) {
> +    case CU_TYPE_VIRTIO:
> +        virtio_setup();
> +        zipl_load(); /* no return */
> +        break;
> +    default:
> +        print_int("Attempting to boot from unexpected device type", cutype);
> +        panic("");
> +    }
>  
>      panic("Failed to load OS from hard disk\n");
>      return 0; /* make compiler happy */