On 25.01.2017 15:42, Laurent Vivier wrote:
> Le 25/01/2017 à 09:40, Thomas Huth a écrit :
>> We can have basic support for the "-kernel" parameter quite easily
>> by using the generic loader device. This should be enough for most
>> boards which do not need special machine-specific magic for loading
>> a kernel (and for those that need special magic, the generic "none"
>> machine is likely not suitable for using it as an instruction set
>> simulator board anyway).
>>
>> Signed-off-by: Thomas Huth <th...@redhat.com>
>> ---
>> PS: If we can't agree on using the generic loader here, I can also
>> prepare a patch instead that simply prints out an error message
>> if the user tried to use the "-kernel" parameter.
>>
>> hw/core/null-machine.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/hw/core/null-machine.c b/hw/core/null-machine.c
>> index 27c8369..866e699 100644
>> --- a/hw/core/null-machine.c
>> +++ b/hw/core/null-machine.c
>> @@ -5,6 +5,7 @@
>> *
>> * Authors:
>> * Anthony Liguori <aligu...@us.ibm.com>
>> + * Thomas Huth <th...@redhat.com>
>> *
>> * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> * See the COPYING file in the top-level directory.
>> @@ -16,6 +17,7 @@
>> #include "qemu/error-report.h"
>> #include "hw/hw.h"
>> #include "hw/boards.h"
>> +#include "hw/core/generic-loader.h"
>> #include "sysemu/sysemu.h"
>> #include "exec/address-spaces.h"
>> #include "cpu.h"
>> @@ -40,6 +42,18 @@ static void machine_none_init(MachineState *mch)
>> memory_region_allocate_system_memory(ram, NULL, "ram",
>> mch->ram_size);
>> memory_region_add_subregion(get_system_memory(), 0, ram);
>> }
>> +
>> + /* Load kernel */
>> + if (mch->kernel_filename) {
>> + DeviceState *loader;
>> +
>> + loader = qdev_create(sysbus_get_default(), TYPE_GENERIC_LOADER);
>> + qdev_prop_set_string(loader, "file", mch->kernel_filename);
>> + if (cpu) {
>> + qdev_prop_set_uint32(loader, "cpu-num", cpu->cpu_index);
>> + }
>> + qdev_init_nofail(loader);
>> + }
>> }
>
> It seems you need to check "-cpu" is set otherwise we have a segfault in
> the loader:
>
> Thread 1 "qemu-system-m68" received signal SIGSEGV, Segmentation fault.
> ...
> #0 0x000055555564e5f8 in generic_loader_realize (dev=<optimized out>,
> errp=0x7fffffffd900) at hw/core/generic-loader.c:141
>
> 140 if (!s->force_raw) {
> 141 size = load_elf_as(s->file, NULL, NULL, &entry, NULL, NULL,
> 142 big_endian, 0, 0, 0, s->cpu->as);
> 143
>
> (gdb) p s->cpu
> $2 = (CPUState *) 0x0
Oh, nice catch! ... but I think this should rather be fixed in the
generic-loader instead, e.g. by using get_system_memory() instead of
s->cpu->as if s->cpu is NULL. Otherwise you can still trigger the crash
if using the loader device directly, e.g. with "-M none -device
loader,file=something". I'll send a separate patch for this...
Thomas
