[Toybox] Vm for lkmpg

[Rob Landley]

On 1/19/25 02:45, Berkem Dincman wrote:
> I'm using System Images for building and executing examples from the Linux
> Kernel Module Guide if I insert a modüle via
> insmod procfs1.ko
> I get the first result
> toybox insmod hello-5.ko
> without the error messages
> just out of curiosity

Try running it under strace? The insmod.c insmod_main() code is 
basically doing:

   rc = syscall(SYS_finit_module, fd, toybuf, 0);
   if (rc && blah) rc = syscall(SYS_init_module, buf, len, toybuf);
   if (rc) perror_exit("failed to load %s", toys.optargs[0]);

Which should print an error if both syscalls fail. The only way NOT to 
print an error is for one or the other syscall to return 0.

Your attached screenshots show dmesg complaining about tainting the 
kernel and ignoring unrecognized parameters, but neither is actually an 
error preventing the module from loading.

Are you sure that's the exact command line you called? It seems weird 
that your second screen shot has parameters winding up in toybuf when 
the command is "<1" requiring at least one argument and then loops 
through from entry 1 of a NULL terminated list (where 0 was the module 
name). If you didn't provide more command line arguments, it should hit 
null the first time through the loop and leave toybox completely 
null-filled...

Although two screenshots being attached with different results is 
already a bit confusing to me...

Rob

P.S. I should really go do more work in the toybox strace in pending. 
There's ancient static strace binaries for various architectures at 
https://landley.net/aboriginal/downloads/old/binaries/1.4.3/extras/ but 
that old system builder project never supported arm64 because the 
compiler went gplv3...