Re: [Qemu-devel] [RFC 3/5] scripts/dump-guest-memory.py: Improve python 3 compatibility

[Janosch Frank <frankja@linux.vnet.ibm.com>]

On 01/14/2016 05:03 PM, Laszlo Ersek wrote:
> On 01/14/16 09:48, Janosch Frank wrote:
>> This commit does not make the script python 3 compatible, it is a
>> preparation that fixes the easy and common incompatibilities.
>>
>> Print is a function in python 3 and therefore needs braces around its
>> arguments.
>>
>> Range does not cast a gdb.Value object to int in python 3, we have to
>> do it ourselves.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
>> ---
>>  scripts/dump-guest-memory.py | 22 +++++++++++-----------
>>  1 file changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
>> index 76a6ecb..fe93135 100644
>> --- a/scripts/dump-guest-memory.py
>> +++ b/scripts/dump-guest-memory.py
>> @@ -98,15 +98,15 @@ def memory_region_get_ram_ptr(mr):
>>  
>>  def get_guest_phys_blocks():
>>      guest_phys_blocks = []
>> -    print "guest RAM blocks:"
>> -    print ("target_start     target_end       host_addr        message "
>> -           "count")
>> -    print ("---------------- ---------------- ---------------- ------- "
>> -           "-----")
>> +    print("guest RAM blocks:")
>> +    print("target_start     target_end       host_addr        message "
>> +          "count")
>> +    print("---------------- ---------------- ---------------- ------- "
>> +          "-----")
>>  
>>      current_map_p = gdb.parse_and_eval("address_space_memory.current_map")
>>      current_map = current_map_p.dereference()
>> -    for cur in range(current_map["nr"]):
>> +    for cur in range(int(current_map["nr"])):
> 
> FlatView.nr has type "unsigned" in C -- is this int cast safe in python?
> (I don't expect a >= 2G value in "nr", but still.)

>From the python point of view it shouldn't matter, short int is at least
32bit, long is arbitrary sized:

The function int() will return a short or a long int depending on
the argument value.
pep-0237

But I do not have enough cpython knowledge to validate what gdb does in
gdb/python/py-value.c as the value is a gdb.Value that gets cast to
integer or long.

> 
> Thanks
> Laszlo
> 
>>          flat_range   = (current_map["ranges"] + cur).dereference()
>>          mr           = flat_range["mr"].dereference()
>>  
>> @@ -149,9 +149,9 @@ def get_guest_phys_blocks():
>>              predecessor["target_end"] = target_end
>>              message = "joined"
>>  
>> -        print ("%016x %016x %016x %-7s %5u" %
>> -               (target_start, target_end, host_addr.cast(UINTPTR_T),
>> -                message, len(guest_phys_blocks)))
>> +        print("%016x %016x %016x %-7s %5u" %
>> +              (target_start, target_end, host_addr.cast(UINTPTR_T),
>> +               message, len(guest_phys_blocks)))
>>  
>>          return guest_phys_blocks
>>  
>> @@ -311,8 +311,8 @@ shape and this command should mostly work."""
>>          for block in self.guest_phys_blocks:
>>              cur  = block["host_addr"]
>>              left = block["target_end"] - block["target_start"]
>> -            print ("dumping range at %016x for length %016x" %
>> -                   (cur.cast(UINTPTR_T), left))
>> +            print("dumping range at %016x for length %016x" %
>> +                  (cur.cast(UINTPTR_T), left))
>>              while (left > 0):
>>                  chunk_size = min(TARGET_PAGE_SIZE, left)
>>                  chunk = qemu_core.read_memory(cur, chunk_size)
>>
>