On 12/12/17 17:35, Marc-André Lureau wrote: > If the script is run with a core (no running process), it produces an > error: > > (gdb) dump-guest-memory /tmp/vmcore X86_64 > guest RAM blocks: > target_start target_end host_addr message count > ---------------- ---------------- ---------------- ------- ----- > 0000000000000000 00000000000a0000 00007f7935800000 added 1 > 00000000000a0000 00000000000b0000 00007f7934200000 added 2 > 00000000000c0000 00000000000ca000 00007f79358c0000 added 3 > 00000000000ca000 00000000000cd000 00007f79358ca000 joined 3 > 00000000000cd000 00000000000e8000 00007f79358cd000 joined 3 > 00000000000e8000 00000000000f0000 00007f79358e8000 joined 3 > 00000000000f0000 0000000000100000 00007f79358f0000 joined 3 > 0000000000100000 0000000080000000 00007f7935900000 joined 3 > 00000000fd000000 00000000fe000000 00007f7934200000 added 4 > 00000000fffc0000 0000000100000000 00007f7935600000 added 5 > Python Exception <class 'gdb.error'> You can't do that without a process to > debug.: > Error occurred in Python command: You can't do that without a process > to debug. > > Replace the function call with a variable.
Can you state, "replace the object_resolve_path_type() function call with an extern variable"? > I tried to use static > function variables, as suggested by Laszlo in earlier reviews, but the > compiler always took the chance to optimize them away. Did you qualify them "volatile" too? E.g., in the vmcoreinfo_realize() function: static VMCoreInfoState * volatile vmcoreinfo_state; ... vmcoreinfo_state = s; (Note: it's the pointer itself that has to be volatile, not the pointed-to object.) If you did try this, but GCC optimized it away, then that's a GCC bug. In that case I guess I can't object to the present approach any longer. Can you please confirm? > > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> > --- > scripts/dump-guest-memory.py | 3 +-- > hw/misc/vmcoreinfo.c | 4 ++++ > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py > index 1af26c1a45..9dec796762 100644 > --- a/scripts/dump-guest-memory.py > +++ b/scripts/dump-guest-memory.py > @@ -546,8 +546,7 @@ shape and this command should mostly work.""" > return None > > def add_vmcoreinfo(self): > - vmci = '(VMCoreInfoState *)' + \ > - 'object_resolve_path_type("", "vmcoreinfo", 0)' > + vmci = 'vmcoreinfo_state' > if not gdb.parse_and_eval("%s" % vmci) \ > or not gdb.parse_and_eval("(%s)->has_vmcoreinfo" % vmci): > return > diff --git a/hw/misc/vmcoreinfo.c b/hw/misc/vmcoreinfo.c > index 31db57ab44..d429a4f7d6 100644 > --- a/hw/misc/vmcoreinfo.c > +++ b/hw/misc/vmcoreinfo.c > @@ -31,6 +31,9 @@ static void vmcoreinfo_reset(void *dev) > s->vmcoreinfo.host_format = cpu_to_le16(VMCOREINFO_FORMAT_ELF); > } > > +/* this variable is exported for gdb script dump-guest-memory.py */ > +VMCoreInfoState *vmcoreinfo_state; > + > static void vmcoreinfo_realize(DeviceState *dev, Error **errp) > { > VMCoreInfoState *s = VMCOREINFO(dev); > @@ -56,6 +59,7 @@ static void vmcoreinfo_realize(DeviceState *dev, Error > **errp) > &s->vmcoreinfo, sizeof(s->vmcoreinfo), false); > > qemu_register_reset(vmcoreinfo_reset, dev); > + vmcoreinfo_state = s; > } > > static const VMStateDescription vmstate_vmcoreinfo = { > Thanks! Laszlo