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

[Alexander Graf <agraf@suse.de>]

On 04/23/2013 10:58 AM, Cornelia Huck wrote:
> On Mon, 22 Apr 2013 21:18:11 +0200
> Alexander Graf<agraf@suse.de>  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<agraf@suse.de>
>> ---
>>   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<agraf@suse.de>
>> + *
>> + * 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