2013/3/24 Peter Maydell <peter.mayd...@linaro.org>:
> On 24 March 2013 17:27, Rabin Vincent <ra...@rab.in> wrote:
>> --- /dev/null
>> +++ b/target-arm/arch_dump.c
>> @@ -0,0 +1,61 @@
>> +#include "cpu.h"
>> +#include "sysemu/dump.h"
>> +#include "elf.h"
>> +
>> +typedef struct {
>> + char pad1[24];
>> + uint32_t pid;
>> + char pad2[44];
>> + uint32_t regs[18];
>> + char pad3[4];
>> +} arm_elf_prstatus;
>
> Can you point me at the spec this struct corresponds to?
This is elf_prstatus from the Linux kernel's
include/uapi/linux/elfcore.h, with the regset begin ARM regs in this
case.
I don't know if there's a spec. It doesn't sound like it from the
comments in the kernel file: "This is mostly like the SVR4 structure,
but more Linuxy, with things that Linux does not support and which gdb
doesn't really use excluded."
The x86 implementation in target-i386/arch_dump.c uses the same
elf_prstatus with the x86 regs.
>
>> +
>> +int cpu_write_elf64_note(write_core_dump_function f, CPUArchState *env,
>> + int cpuid, void *opaque)
>> +{
>> + return -1;
>> +}
>
> Is there any documentation of the API we're implementing here?
I coudn't find any documentation. It's only x86 that has the API
implemented.
> (why does it require us to provide 64 bit functions that are
> never used?)
I guess the API was made with x86 in mind. I will see if the
requirement can be removed with some ifdefs in the dump.c file.
(come to think of it, I guess this ARM code will need to use ELFCLASS64
when we have physical memory > 4GiB (LPAE))
>> +int cpu_write_elf32_qemunote(write_core_dump_function f, CPUArchState *env,
>> + void *opaque)
>> +{
>> + return 0;
>> +}
>
> Why is it OK to implement this as a no-op? What could we
> be doing here that we don't do? What are the effects?
This is supposed to be used to add some additional information about the
CPU state in an ELF note in a QEMU-specific structure, like the
QEMUCPUState in target-i386/arm-state.c. It's only useful to implement
this if someone sees a need to add any such information.
>
>> +
>> +int cpu_get_dump_info(ArchDumpInfo *info)
>> +{
>> + info->d_machine = EM_ARM;
>> +#ifdef TARGET_WORDS_BIGENDIAN
>> + info->d_endian = ELFDATA2MSB;
>> +#else
>> + info->d_endian = ELFDATA2LSB;
>> +#endif
>> + info->d_class = ELFCLASS32;
>
> Most of this looks like it would be suitable for a default
> implementation that said "endian based on TARGET_WORDS_BIGENDIAN,
> machine is ELF_MACHINE, class based on TARGET_LONG_BITS".
I will see if this can be moved into the generic dump.c.
