Re: [lwip-users] Mailboxes and Semaphores

[Timmy Brolin]

How about mailboxes? Does LwIP require multiple waiting threads on a
mailbox? That would require some substantial rewriting of our OS mailbox
system.
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

address@hidden 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
>>
>>
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