Python DevMem
This is designed primarily for use with accessing /dev/mem on OMAP platforms. It should work on other platforms and work to mmap() files rather then just /dev/mem, but these use cases aren't well tested.
All file accesses are aligned to DevMem.word bytes, which is 4 bytes on ARM platforms to avoid data abort faults when accessing peripheral registers.
Usage
Usage: devmem.py [options]
Options:
-h, --help show this help message and exit
-r ADDR, --read=ADDR read a value
-w ADDR VALUE, --write=ADDR VALUE
write a value
-n NUM, --num=NUM number of words to read
-s WORD_SIZE, --word-size=WORD_SIZE
size of word when displayed
-m FILE, --mmap=FILE file to open with mmap()
-v provide more information regarding operation
-d provide debugging information
Speed
Initial testing on a BeagleBoard-xM (Cortex-A8 in a TI DM3730) shows that starting up the python interpreter is pretty slow:
# time (echo | python)
real 0m0.859s
user 0m0.750s
sys 0m0.102s
# time python ./pydevmem.py -r 0x4830a204 -n 8
0x4830a204: 1b89102f 00000000 00000000 000000f0
0x4830a214: cafeb891 0c030016 015739eb 1ff00000
real 0m1.109s
user 0m0.977s
sys 0m0.133s
# time python -S ./pydevmem.py -r 0x4830a204 -n 8
0x4830a204: 1b89102f 00000000 00000000 000000f0
0x4830a214: cafeb891 0c030016 015739eb 1ff00000
real 0m0.659s
user 0m0.602s
sys 0m0.047s
# time python -S ./pydevmem.pyc -r 0x4830a204 -n 8
0x4830a204: 1b89102f 00000000 00000000 000000f0
0x4830a214: cafeb891 0c030016 015739eb 1ff00000
real 0m0.647s
user 0m0.508s
sys 0m0.133s
System information for those tests:
Linux omap 3.0.6-x3 #1 SMP Wed Oct 5 07:19:24 UTC 2011 armv7l GNU/Linux
python 2.7.2-7ubuntu2
python-configobj 4.7.2+ds-3
python-minimal 2.7.2-7ubuntu2
python2.7 2.7.2-5ubuntu1
python2.7-minimal 2.7.2-5ubuntu1
Something needs to be sped up to make python start-up in a reasonable amount of time.