>> On 2023/06/12 12:42, Viktor Prutyanov wrote:
>>
>>>> Prcb may be set to 0 for some CPUs if the dump was taken before they
>>>> start. The dump may still contain valuable information for started CPUs
>>>> so don't abandon conversion in such a case.
>>>>
>>>> Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
>>>> ---
>>>> contrib/elf2dmp/main.c | 5 +++++
>>>> 1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/contrib/elf2dmp/main.c b/contrib/elf2dmp/main.c
>>>> index d77b8f98f7..91c58e4424 100644
>>>> --- a/contrib/elf2dmp/main.c
>>>> +++ b/contrib/elf2dmp/main.c
>>>> @@ -312,6 +312,11 @@ static int fill_context(KDDEBUGGER_DATA64 *kdbg,
>>>> return 1;
>>>> }
>>>>
>>>> + if (!Prcb) {
>>>> + eprintf("Context for CPU #%d is missing\n", i);
>>>> + continue;
>>>> + }
>>>> +
>>>> if (va_space_rw(vs, Prcb + kdbg->OffsetPrcbContext,
>>>> &Context, sizeof(Context), 0)) {
>>>> eprintf("Failed to read CPU #%d ContextFrame location\n", i);
>>>>
>>>> --
>>>> 2.40.1
>>>
>>> Hi Akihiko,
>>>
>>> How this fix can be tested?
>>
>> It is a bit difficult to test it as you need to interrupt the very early
>> stage of boot. I applied the following change to TCG so that it stops
>> immediately after the first processor configures Prcb.
>>
>> diff --git a/target/i386/tcg/sysemu/misc_helper.c
>> b/target/i386/tcg/sysemu/misc_helper.c
>> index e1528b7f80..f68eba9cac 100644
>> --- a/target/i386/tcg/sysemu/misc_helper.c
>> +++ b/target/i386/tcg/sysemu/misc_helper.c
>> @@ -25,6 +25,9 @@
>> #include "exec/address-spaces.h"
>> #include "exec/exec-all.h"
>> #include "tcg/helper-tcg.h"
>> +#include "exec/gdbstub.h"
>> +#include "hw/core/cpu.h"
>> +#include "sysemu/runstate.h"
>>
>> void helper_outb(CPUX86State *env, uint32_t port, uint32_t data)
>> {
>> @@ -217,7 +220,10 @@ void helper_wrmsr(CPUX86State *env)
>> env->segs[R_FS].base = val;
>> break;
>> case MSR_GSBASE:
>> + printf("%s: %" PRIx64 "\n", __func__, val);
>> env->segs[R_GS].base = val;
>> + gdb_set_stop_cpu(current_cpu);
>> + vm_stop(RUN_STATE_PAUSED);
>> break;
>> case MSR_KERNELGSBASE:
>> env->kernelgsbase = val;
>>
>>> NumberProcessors field is still set to qemu_elf.state_nr, how does WinDbg
>>> react to this?
>>
>> If Prcb for processor 1 is missing, WinDbg outputs: KiProcessorBlock[1]
>> is null.
>> You can still debug the started processors with no issue.
>>
>> Regards,
>> Akihiko Odaki
>>
>>> Viktor
>
> Reviewed-by: Viktor Prutyanov <viktor.prutya...@phystech.edu>
Hi Peter,
Could you please put Akihiko's patch into your branch?
Thank you,
Viktor Prutyanov
