[v2] dump-guest-memory: more descriptive lookup_type failure

We've seen a few reports of

 (gdb) source /usr/share/qemu-kvm/dump-guest-memory.py
 Traceback (most recent call last):
   File "/usr/share/qemu-kvm/dump-guest-memory.py", line 19, in <module>
     UINTPTR_T = gdb.lookup_type("uintptr_t")
 gdb.error: No type named uintptr_t.

This occurs when symbols haven't been loaded first, i.e. neither a
QEMU binary was loaded nor a QEMU process was attached first. Let's
better inform the user of how to fix the issue themselves in order
to avoid more reports.

Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
v2: Not quite so long a long line (< 90 only generates warnings)
    Pick up Janosch's ack

 scripts/dump-guest-memory.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

On Wed, 03/14 16:38, Andrew Jones wrote:
> We've seen a few reports of
> 
>  (gdb) source /usr/share/qemu-kvm/dump-guest-memory.py
>  Traceback (most recent call last):
>    File "/usr/share/qemu-kvm/dump-guest-memory.py", line 19, in <module>
>      UINTPTR_T = gdb.lookup_type("uintptr_t")
>  gdb.error: No type named uintptr_t.
> 
> This occurs when symbols haven't been loaded first, i.e. neither a
> QEMU binary was loaded nor a QEMU process was attached first. Let's
> better inform the user of how to fix the issue themselves in order
> to avoid more reports.
> 
> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
> v2: Not quite so long a long line (< 90 only generates warnings)
>     Pick up Janosch's ack
> 
>  scripts/dump-guest-memory.py | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
> index 51acfcd0c053..276eebf0c27e 100644
> --- a/scripts/dump-guest-memory.py
> +++ b/scripts/dump-guest-memory.py
> @@ -16,7 +16,12 @@ the COPYING file in the top-level directory.
>  import ctypes
>  import struct
>  
> -UINTPTR_T = gdb.lookup_type("uintptr_t")
> +try:
> +    UINTPTR_T = gdb.lookup_type("uintptr_t")
> +except Exception as inst:
> +    raise gdb.GdbError("Symbols must be loaded prior to sourcing dump-guest-memory.\n"
> +                       "Symbols may be loaded by 'attach'ing a QEMU process id or by "
> +                       "'load'ing a QEMU binary.")
>  
>  TARGET_PAGE_SIZE = 0x1000
>  TARGET_PAGE_MASK = 0xFFFFFFFFFFFFF000
> -- 
> 2.13.6
> 
> 

Reviewed-by: Fam Zheng <famz@redhat.com>
Tested-by: Fam Zheng <famz@redhat.com>

On 03/14/18 16:38, Andrew Jones wrote:
> We've seen a few reports of
> 
>  (gdb) source /usr/share/qemu-kvm/dump-guest-memory.py
>  Traceback (most recent call last):
>    File "/usr/share/qemu-kvm/dump-guest-memory.py", line 19, in <module>
>      UINTPTR_T = gdb.lookup_type("uintptr_t")
>  gdb.error: No type named uintptr_t.
> 
> This occurs when symbols haven't been loaded first, i.e. neither a
> QEMU binary was loaded nor a QEMU process was attached first. Let's
> better inform the user of how to fix the issue themselves in order
> to avoid more reports.
> 
> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
> v2: Not quite so long a long line (< 90 only generates warnings)
>     Pick up Janosch's ack
> 
>  scripts/dump-guest-memory.py | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
> index 51acfcd0c053..276eebf0c27e 100644
> --- a/scripts/dump-guest-memory.py
> +++ b/scripts/dump-guest-memory.py
> @@ -16,7 +16,12 @@ the COPYING file in the top-level directory.
>  import ctypes
>  import struct
>  
> -UINTPTR_T = gdb.lookup_type("uintptr_t")
> +try:
> +    UINTPTR_T = gdb.lookup_type("uintptr_t")
> +except Exception as inst:
> +    raise gdb.GdbError("Symbols must be loaded prior to sourcing dump-guest-memory.\n"
> +                       "Symbols may be loaded by 'attach'ing a QEMU process id or by "
> +                       "'load'ing a QEMU binary.")
>  
>  TARGET_PAGE_SIZE = 0x1000
>  TARGET_PAGE_MASK = 0xFFFFFFFFFFFFF000
> 

Ah, cool.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks!
Laszlo