Timmy Brolin wrote:
How about mailboxes? Does LwIP require multiple waiting threads on a
mailbox? That would require some substantial rewriting of our OS mailbox
system.
I don't think that's necessary: mailboxes are currently used
a) for the tcpip_thread to process input packets and other actions from
other threads in the main lwip thread and
b) for queueing input packets on normal connections / newly accepted
connections on tcp listening connections
Since lwip does not support multiple threads to use one socket/netconn
simultaneously, you won't have any problem here.
However, this is not an official statement about mbox requirements, so
it could be (although not very likely) that things change, especially
when it comes to multithread-usage of sockets. But even if so, you might
still be able to avoid those situations. After all, having multiple
listeners on an mbox does not make sense to me in the situation of this
stack, as results are not predictable.
Simon
I think it would be pretty straight forward to add support for
semaphore/mailbox deallocation to our OS, so that is not a very big issue.
Regards,
Timmy Brolin
goldsi...@gmx.de wrote:
If I remember correctly, there are many places in the stack where your
simple semaphore can be used (tcpip_thread, netconn semaphores, etc.)
but there are also other usages where multiple waiting threads have to
be supported (i.e. locking the heap in mem_malloc). So I guess you are
right that the generic sys_sem_t must be the multiple-type.
Speaking of deallocation: I also ran lwIP on an OS which didn't
support this. I ended up in having a preallocated list/array of
mboxes/semaphores and returning an instance of that list in
sys_sem_new().
Simon
Timmy Brolin wrote:
Hello,
I have A few questions about LwIP OS requirements..
Our operating system provides two kinds of semaphores. The normal (and
resource-light) semaphore only allows a single task to block on it at
any one time. There is also a second type which allows multiple tasks to
block on it at the same time, but it requires a bit more memory
resources.
Am I correct in assuming that LwIP requires multiple tasks to block on
the same semaphore? Are there any semaphores in LwIP which could do with
the simpler semaphore type?
The mailbox system in our operating system is based on the standard
semaphores, so only one task may block on a mailbox at any one time. Is
this acceptable for LwIP?
Our OS has a limitation in that semaphores and mailboxes never can be
deallocated, and I was hoping that the addition of a deallocation
funtion for semaphores and mailboxes would be enough to get LwIP running
on our system. I would prefer not having to write a new mailbox system
as well.. :-)
Regards,
Timmy Brolin
_______________________________________________
lwip-users mailing list
lwip-users@nongnu.org
http://lists.nongnu.org/mailman/listinfo/lwip-users
_______________________________________________
lwip-users mailing list
lwip-users@nongnu.org
http://lists.nongnu.org/mailman/listinfo/lwip-users
_______________________________________________
lwip-users mailing list
lwip-users@nongnu.org
http://lists.nongnu.org/mailman/listinfo/lwip-users
_______________________________________________
lwip-users mailing list
lwip-users@nongnu.org
http://lists.nongnu.org/mailman/listinfo/lwip-users
