We're going to use the s390x boot code for testing CD-ROM booting.
But the ISO loader of the s390-ccw bios is a little bit more picky
than the network loader and expects some magic bytes in the header
of the file (see linux_s390_magic in pc-bios/s390-ccw/bootmap.c), so
we've got to add them in our boot code here, too.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/boot-sector.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tests/boot-sector.c b/tests/boot-sector.c
index c373f0e..7824286 100644
--- a/tests/boot-sector.c
+++ b/tests/boot-sector.c
@@ -68,8 +68,11 @@ static uint8_t x86_boot_sector[512] = {
 };
 
 /* For s390x, use a mini "kernel" with the appropriate signature */
-static const uint8_t s390x_psw[] = {
-    0x00, 0x08, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00
+static const uint8_t s390x_psw_and_magic[] = {
+    0x00, 0x08, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00,  /* Program status word  */
+    0x02, 0x00, 0x00, 0x18, 0x60, 0x00, 0x00, 0x50,  /* Magic:               */
+    0x02, 0x00, 0x00, 0x68, 0x60, 0x00, 0x00, 0x50,  /* see linux_s390_magic */
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40   /* in the s390-ccw bios */
 };
 static const uint8_t s390x_code[] = {
     0xa7, 0xf4, 0x00, 0x0a,                                /* j 0x10010 */
@@ -110,7 +113,7 @@ int boot_sector_init(char *fname)
     } else if (g_str_equal(arch, "s390x")) {
         len = 0x10000 + sizeof(s390x_code);
         boot_code = g_malloc0(len);
-        memcpy(boot_code, s390x_psw, sizeof(s390x_psw));
+        memcpy(boot_code, s390x_psw_and_magic, sizeof(s390x_psw_and_magic));
         memcpy(&boot_code[0x10000], s390x_code, sizeof(s390x_code));
     } else {
         g_assert_not_reached();
-- 
1.8.3.1

On 03/16/2018 06:39 AM, Thomas Huth wrote:
> We're going to use the s390x boot code for testing CD-ROM booting.
> But the ISO loader of the s390-ccw bios is a little bit more picky
> than the network loader and expects some magic bytes in the header
> of the file (see linux_s390_magic in pc-bios/s390-ccw/bootmap.c), so
> we've got to add them in our boot code here, too.
> 
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/boot-sector.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/boot-sector.c b/tests/boot-sector.c
> index c373f0e..7824286 100644
> --- a/tests/boot-sector.c
> +++ b/tests/boot-sector.c
> @@ -68,8 +68,11 @@ static uint8_t x86_boot_sector[512] = {
>  };
>  
>  /* For s390x, use a mini "kernel" with the appropriate signature */
> -static const uint8_t s390x_psw[] = {
> -    0x00, 0x08, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00
> +static const uint8_t s390x_psw_and_magic[] = {
> +    0x00, 0x08, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00,  /* Program status word  */
> +    0x02, 0x00, 0x00, 0x18, 0x60, 0x00, 0x00, 0x50,  /* Magic:               */
> +    0x02, 0x00, 0x00, 0x68, 0x60, 0x00, 0x00, 0x50,  /* see linux_s390_magic */
> +    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40   /* in the s390-ccw bios */
>  };
>  static const uint8_t s390x_code[] = {
>      0xa7, 0xf4, 0x00, 0x0a,                                /* j 0x10010 */
> @@ -110,7 +113,7 @@ int boot_sector_init(char *fname)
>      } else if (g_str_equal(arch, "s390x")) {
>          len = 0x10000 + sizeof(s390x_code);
>          boot_code = g_malloc0(len);
> -        memcpy(boot_code, s390x_psw, sizeof(s390x_psw));
> +        memcpy(boot_code, s390x_psw_and_magic, sizeof(s390x_psw_and_magic));
>          memcpy(&boot_code[0x10000], s390x_code, sizeof(s390x_code));
>      } else {
>          g_assert_not_reached();
>