socket system call from python

While the Python socket API is mature, it does not yet support MCTP. I thought I would thus try to make a call from python into native code. The first step is to create a socket. Here is my code to do that.

Note that this is not the entire C code needed to make network call, just the very first step.I did include the code to read errno if the call fails.

from ctypes import *
libc = CDLL("/lib64/")
AF_MCTP = 45
rc = libc.socket (AF_MCTP, SOCK_DGRAM, 0)
#print("rc = %d " % rc)
get_errno_loc = libc.__errno_location
get_errno_loc.restype = POINTER(c_int)
errno = get_errno_loc()[0]
print("rc = %d errno =  %d" % (rc, errno)   )

Running this code on my machine shows success

# ./ 
rc = 3 errno =  0

Querying the PCCT in Python

The Platform Communication Channel Table contains information used to send messages in a shared memory buffer between the Operating System and other subsystems on the platform. Typically, the Channel has an interrupt defined that is used to tell the other subsystem that there is new data available.

Recently, I’ve been working with a couple entries that are of a newer type. In addition to the shared memory region and the interrupt values, the PCCT entries for type 3 and type 4 channels also have a series of registers. Where before the PCCT entries were normalized, now they are hierarchical. This makes them a little harder to scan with the human eye to confirm that the proper values have been recorded and read.

To simplify development, I build a simple script.

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Hidden Tuples

If you are going to write a Sudoku solver, write a brute force, depth first search. You can get it running fast enough.

But what if you couldn’t? What if the puzzles were so big that solving them by brute force was not computationally feasible? A Sudoku puzzle is build on a basis of 3: The Blocks are 3X3, there are 3X 3 of them in the puzzle, and the rows and columns are are 9 cells (3 * 3) long. This approach scales up. If you were to do a basis of 4, you could use the Hexadecimal digits, and have 16 X 16 puzzles.

A Basis of K leads to a puzzle size of (K^4). The basis can be any integer. A Basis of 10 would lead to a puzzle size of 1000.

The Sudoku puzzle shows exponential growth.

What could you do for a complex puzzle? Use heuristics to reduce the problem set to the point where a the brute force algorithm can complete.

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