diff options
| author | Alexey Kardashevskiy <aik@ozlabs.ru> | 2022-05-04 16:55:36 +1000 |
|---|---|---|
| committer | Daniel Henrique Barboza <danielhb413@gmail.com> | 2022-05-26 17:11:32 -0300 |
| commit | 5bb55f3e3b00679519a83ffe688eae0e68e305a7 (patch) | |
| tree | 563713725915885b62c31b9d9aa383beaa3867d1 /hw/ppc | |
| parent | 1e665723e92cd3dae4d8943bf7bd1799a3b4a82a (diff) | |
spapr: Use address from elf parser for kernel address
tl;dr: This allows Big Endian zImage booting via -kernel + x-vof=on.
QEMU loads the kernel at 0x400000 by default which works most of
the time as Linux kernels are relocatable, 64bit and compiled with "-pie"
(position independent code). This works for a little endian zImage too.
However a big endian zImage is compiled without -pie, is 32bit, linked to
0x4000000 so current QEMU ends up loading it at
0x4400000 but keeps spapr->kernel_addr unchanged so booting fails.
This uses the kernel address returned from load_elf().
If the default kernel_addr is used, there is no change in behavior (as
translate_kernel_address() takes care of this), which is:
LE/BE vmlinux and LE zImage boot, BE zImage does not.
If the VM created with "-machine kernel-addr=0,x-vof=on", then QEMU
prints a warning and BE zImage boots.
Note #1: SLOF (x-vof=off) still cannot boot a big endian zImage as
SLOF enables MSR_SF for everything loaded by QEMU and this leads to early
crash of 32bit zImage.
Note #2: BE/LE vmlinux images set MSR_SF in early boot so these just work;
a LE zImage restores MSR_SF after every CI call and we are lucky enough
not to crash before the first CI call.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20220504065536.3534488-1-aik@ozlabs.ru>
[danielhb: use PRIx64 instead of lx in warn_report]
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Diffstat (limited to 'hw/ppc')
| -rw-r--r-- | hw/ppc/spapr.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index d112b85b4f..fd4942e881 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2975,14 +2975,16 @@ static void spapr_machine_init(MachineState *machine) } if (kernel_filename) { + uint64_t loaded_addr = 0; + spapr->kernel_size = load_elf(kernel_filename, NULL, translate_kernel_address, spapr, - NULL, NULL, NULL, NULL, 1, + NULL, &loaded_addr, NULL, NULL, 1, PPC_ELF_MACHINE, 0, 0); if (spapr->kernel_size == ELF_LOAD_WRONG_ENDIAN) { spapr->kernel_size = load_elf(kernel_filename, NULL, translate_kernel_address, spapr, - NULL, NULL, NULL, NULL, 0, + NULL, &loaded_addr, NULL, NULL, 0, PPC_ELF_MACHINE, 0, 0); spapr->kernel_le = spapr->kernel_size > 0; } @@ -2992,6 +2994,13 @@ static void spapr_machine_init(MachineState *machine) exit(1); } + if (spapr->kernel_addr != loaded_addr) { + warn_report("spapr: kernel_addr changed from 0x%"PRIx64 + " to 0x%"PRIx64, + spapr->kernel_addr, loaded_addr); + spapr->kernel_addr = loaded_addr; + } + /* load initrd */ if (initrd_filename) { /* Try to locate the initrd in the gap between the kernel |