Appreciate your patience to read this slightly long mail and answer.
I am trying trying to do File transfer over Ethernet using my own protocol
(non-IP). I read the contents in chunks (within the kernel, similar to
generic_file_read()), packetize it and send it across. I get the packet at
the other end (the contents are fine) and write it to the file (in either
of the two ways).
1. Using a routine similar to ext2_file_write() but the difference being,
I do a memcpy() from the skbuff instead of the copy_from_user().
PROBLEM: This works fine for files as large as 1MB but has problems
for larger files like 25, 50MB files. I just get a huge dump and I
can't even trace the calls. So, I don't know what is happening.
2. I mmap the output file using do_mmap() within the kernel and I memcpy
the contents of the skbuff to this memory mapped buffer (Since do_mmap
returns a user buffer, I map it to a kernel address and use this for
memcpy. The user-kernel memory mapping part works fine, I have tested
that independently). When I print out the contents of this buffer, it
has the data which came from the skbuff. The memcpy is fine, in the
sense that it doesn't panic/hang.
PROBLEM: After the transfer, when I look at the contents of the file,
it just has zeros.
I have tried transferring files within the kernel (on the same
machine) using do_mmap() for both input and output files. It just works
The communication part (transfer over Ethernet) works fine. i.e. if I just
send dummy packets, I get it at the other end without problems.
Could anyone help me debug the problem?
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This archive was generated by hypermail 2b29 : Wed May 31 2000 - 21:00:11 EST