[Qemu-devel] [PATCH for-1.7] s390x: fix flat rom load on 32 bit systems

["Michael S. Tsirkin" <mst@redhat.com>]

pc-bios/s390-zipl.rom is a flat image so it's expected that
loading it as elf will fail.
It should fall back on loading a flat file, but doesn't
on 32 bit systems, instead it fails printing:
    qemu: hardware error: could not load bootloader 's390-zipl.rom'

The result is boot failure.

The reason is that a 64 bit unsigned interger which is set
to -1 on error is compared to -1UL which on a 32 bit system
with gcc is a 32 bit unsigned interger.
Since both are unsigned, no sign extension takes place and
comparison evaluates to non-equal.

There's no reason to do clever tricks: -1 will cause
sign extension to happen correctly automatically.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/s390x/ipl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index d69adb2..88115e9 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -80,7 +80,7 @@ static int s390_ipl_init(SysBusDevice *dev)
 
         bios_size = load_elf(bios_filename, NULL, NULL, &ipl->start_addr, NULL,
                              NULL, 1, ELF_MACHINE, 0);
-        if (bios_size == -1UL) {
+        if (bios_size == -1) {
             bios_size = load_image_targphys(bios_filename, ZIPL_IMAGE_START,
                                             4096);
             ipl->start_addr = ZIPL_IMAGE_START;
-- 
MST