Hello Marc-F.,
this is what I could make out so far. The functions that support "select"
are implemented in elks/fs/select.c. KTCP does the following select call:
„select(sfd > tcpdevfd ? sfd + 1 : tcpdevfd + 1, &fdset, NULL, NULL, tv);“
In there sfd is the file descriptor for slip and tcpdevfd is the file
descriptor for the tcpdev device.
The tcpdev device has made its tcp_select() function known to the kernel
using the tcp_fops structure via the register_chrdev() function. The kernel
calls this function when loading the module. So the kernel can call
tcp_select() to determine if there is anything to do.
After slip opens the ttySx device, the kernel will query the tty_select()
function in the arch/i86/drivers/char/ntty driver. I think that again calls
rs_ioctl() in serial.c. The structure "tty" which is returned by this
function contains a pointer to the queue of received chars and the select
function in ntty uses that to determine if data has been received and is
available for a read call.
One could probably just make a quick and dirty solution and poll the network
card code for data from the ktcp_run() loop without select. The slip_process
function just returns if no data has been read.
To follow the Linux structure, however, you would have to write an „ethx“
device driver which supports a select call from the kernel.
I am about to finish an "Introduction to ELKS" document this week. The
document is intended to provide a quick start for new users/developers of
ELKS. This document contains a chapter how to write a kernel mode driver for
ELKS although is not typically part of an introduction. If you have not
written such a driver yet this could be of help for developing an „ethx“
device driver.
Georg
-----Ursprüngliche Nachricht-----
From: Marc-F. LUCCA-DANIAU
Sent: Sunday, February 5, 2017 12:12 PM
To: ELKS
Subject: Guidelines to plug NE2K driver in ELKS
Hello all,
As suggested by Alan and Jody, I delivered a standalone code to drive
the NE2K in /elks/arch/i86/drivers/net as a first step, and I intend to
connect it to the low end of KTCP (in parallel of SLIP) as a second step.
But because KTCP needs a "selectable" device to operate, and because I
am not at ease with the select / poll implementation in ELKS, could I
have some guidelines to integrate the current standalone code ?
Thanks,
MFLD
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