The routines listed above aren't in the kernel. They're in libc just
like routines such as printf, memcpy, etc. The above libc routines do
make system calls into the kernel to perform the desired functions, but
those routines are not in the kernel, and calling them is certainly not
"kernel coding".
Yes, Python provides specific wrappers for many C library functions.
Yes, the ctypes module provides a generic method for calling foreign
library functions.
No, using those wrappers is not what anybody I know would call "kernel
coding".
As far as I know, Python doesn't provide the user with the ability to
make system calls into the kernel. Even if it did, that isn't really
"kernel coding" either. It's just making system calls.
Didn't somebody once demonstrate how to put a VM into kernel space so
that you could write kernel code in Python? Maybe it was just a
discussion about how it could be done in theory.
There have been a few JVM-in-hardware projects, so I suppose you could
use Jython to write kernel code for those machines.
I can't understand why somebody might want to do kernel stuff in Python.
It's a *high level language*. It's for high level stuff.
OTOH Python can be easily extended to get as close to the kernel as
anyone may ever need.
I decided to change my "hello world" post to use Linux system call
instead of printf.
#include <Python.h>
PyObject*
hello(PyObject* self)
{
#if defined(__GNUC__) && defined(__i386__) && defined(__linux__)
const char * hello_str = "Hello world (Linux system call)!\n";
int hello_len = 33;
asm __volatile__(
"push %%ebx;"
"movl $4, %%eax;" /* The system call for write (sys_write) */
"movl $1, %%ebx;" /* File descriptor 1 - standard output */
"int $0x80;"
"pop %%ebx;"
: /* no outputs */
: "c" (hello_str), "d" (hello_len) /* input */
);
#else
printf("Hello world!\n");
#endif
Py_RETURN_NONE;
}
static PyMethodDef functions[] = {
{"hello", (PyCFunction)hello, METH_NOARGS},
{NULL, NULL, 0, NULL},
};
DL_EXPORT(void)
init_hello(void)
{
Py_InitModule("_hello", functions);
}
Python 2.5.2 (r252:60911, Apr 21 2008, 11:12:42)
[GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.Hello world (Linux system call)!
I'm in the mood to write "Hello world" programs today
Ivan
