I get the following warning when compiling the latest snapshot. I had
a quick look at the source -- it certainly looks to me like this is a
real bug.
../../../../src/rtems-19990709/c/src/lib/libc/mount.c:97: warning:
`options' might be used uninitialized in this function
Also, I changed the TFTP test program and TFTP driver to reflect the
changes in the way paths are passed to the TFTP driver. The TFTP driver
now needs a proper `dotted-decimal' hostname as the second component of
the path name.
The select function is not particularly efficient when dealing with a
large number of sockets. The application has to build a big set of
bits and pass it in. RTEMS has to look through all those bits and see
what is ready. Then the application has to look through all the bits
again.
On the other hand, when using RTEMS, the select function is needed
exactly when you have a large number of sockets, because that is when
it becomes prohibitive to use a separate thread for each socket.
I think it would make more sense for RTEMS to support callback
functions which could be invoked when there is data available to read
from a socket, or when there is space available to write to a socket.
Accordingly, I implemented them.
This patch adds two new SOL_SOCKET options to setsockopt and
getsockopt: SO_SNDWAKEUP and SO_RCVWAKEUP. They take arguments of
type struct sockwakeup:
struct sockwakeup {
void (*sw_pfn) __P((struct socket *, caddr_t));
caddr_t sw_arg;
};
They are used to add or remove a function which will be called when
something happens for the socket. Getting a callback doesn't imply
that a read or write will succeed, but it does imply that it is worth
trying.
This adds functionality to RTEMS which is somewhat like interrupt
driven socket I/O on Unix.
After the patch to RTEMS, I have appended a patch to
netdemos-19990407/select/test.c to test the new functionality and
demonstrate one way it might be used. To run the new test instead of
the select test, change doSocket to call echoServer2 instead of
echoServer.
Ian Lance Taylor <ian@airs.com>:
Ian Lance Taylor wrote:
>
> In rtems-19990528, sbwait sets SB_WAIT in sb_flags. sowakeup checks
> it. Why doesn't socket_select set it?
>
> I don't know that this is a bug--I haven't tried to create a test
> case. However, it certainly looks odd.
>
> Ian
Yes, there's a bug there. Sorry about that.
It was introduced when I did some cleanup on the sleep/wakeup handling
in rtems_glue.c.
allows one to trace the enqueueing and dequeueing of messages. This
can be used to insure that packets are getting to the boundary between
the network stack and the device driver.
From: Eric Norum <eric@skatter.usask.ca>
Date: Sat, 5 Dec 98 13:20:51 -0600
What do you think of this patch? It implements your `tap'
suggestion in a way that adds support for all ethernet devices with
no driver modifications. I also added a return value from the tap
function. If the return value is zero, the packet will be passed up
the chain as usual. If the return value is non-zero the mbuf holding
the packet will be freed and the packet will be dropped.
If you like it, please submit it to Joel.
I guess there needs to be an addition to the network documentation
describing the additional ioctl's -- and a big warning that the tap
function is called from a context that holds the network semaphore.
Here is Eric's patch. I've tested it a bit, and made a couple of
trivial changes. This is certainly better than mine: it should work
for all Ethernet drivers.
==================================================
The only concern I have about this patch is that the tap function may
want to fiddle with the mbuf, calling functions like m_pullup and the
like. If those force the networking code to rearrange the mbuf
structure, then the caller's call to m_freem may crash. I don't know
if this is a realistic concern--I don't know enough about the mbuf
layer.
RTEMS permits using the SO_SNDTIMEO and SO_RCVTIMEO socket options to
set a timeout for most socket I/O operations. However, in RTEMS
4.0.0, those options do not affect connect or accept. I don't know of
any way to put a timeout on those calls in RTEMS 4.0.0; can anybody
point to one.
Since it is frequently useful to have a timeout on accept, and
sometimes useful to have a timeout on connect shorter than the BSD
system default of 75 seconds, the following patch causes SO_RCVTIMEO
to affect connect and accept.
1) Socket timeout field changed from `short' to `long'. This makes longer
timeouts possible. With a 1 kHz system clock the old system allowed
timeouts only up to a little over 30 seconds! This change is a
slightly cleaned-up version of the patch proposed by Ian Lance Taylor.
2) Major changes to BOOTP/DHCP reply handling. Now supports much of
RFC2132. These changes were done at the request of, and with the
assistance of, Erik Ivanenko.
If you're making changes, you might want to change the network
supplement Essentially just do a global search and replace of BOOTP
with BOOTP/DHCP.
Remember the test to see if a socket could be read and written at
the same time by two different tasks? I discovered that if both
tasks attempt to close the socket a panic can occur from inside the
BSD code.
Closing the same socket twice from two different threads is
certainly an error, but a panic is not the greatest error reporting
method :-)
The following small change to the socket close routine should reduce
the chances of the panic.
Here's a patch to make the rtems_showroute routine a little more
useful. For `host' route table entries the link-level address is now
displayed. This is equivalent to the old `show arp table'
information displayed by the KA9Q code.
