On 30/03/2023 17.33, Peter Maydell wrote:
On Thu, 30 Mar 2023 at 16:27, Thomas Huth <th...@redhat.com> wrote:
Booting a Linux kernel with the malta machine is currently broken
on big endian hosts. The cpu_to_gt32 macro wants to byteswap a value
for little endian targets only, but uses the wrong way to do this:
cpu_to_[lb]e32 works the other way round on big endian hosts! Fix
it by using the same ways on both, big and little endian hosts.
Fixes: 0c8427baf0 ("hw/mips/malta: Use bootloader helper to set BAR registers")
Signed-off-by: Thomas Huth <th...@redhat.com>
---
I've checked that both, the kernel from
https://landley.net/toybox/downloads/binaries/mkroot/0.8.9/mipsel.tgz
and the kernel from
https://landley.net/toybox/downloads/binaries/mkroot/0.8.9/mips.tgz
now boot fine on both, a little endian (x86) and a big endian (s390x) host.
hw/mips/malta.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/hw/mips/malta.c b/hw/mips/malta.c
index af9021316d..b26ed1fc9a 100644
--- a/hw/mips/malta.c
+++ b/hw/mips/malta.c
@@ -629,9 +629,9 @@ static void bl_setup_gt64120_jump_kernel(void **p, uint64_t
run_addr,
/* Bus endianess is always reversed */
#if TARGET_BIG_ENDIAN
-#define cpu_to_gt32 cpu_to_le32
+#define cpu_to_gt32(x) (x)
#else
-#define cpu_to_gt32 cpu_to_be32
+#define cpu_to_gt32(x) bswap32(x)
#endif
So if we:
* do nothing to the value on a BE host
* swap the value on an LE host
isn't that the same as cpu_to_be32() in both cases?
No, it's about the *target*, not the host:
* do nothing to the value for a BE *target*
* swap the value for LE *targets*
It's quite weird and it also took me a while to understand this, but this
seems to be the way it's working right with all combinations.
Thomas
