lock

[Jeff Johnston]

Rosière mathieu wrote:
> Hi,
> 
> I have a system with multi cpu. All thread running on each cpu, and
> write a message on a tty. But the primitive of lock (in <sys/lock.h>) is
> not implemented. (in configure.host, i have set the flag
> newlib_multithread)
> 
> * Have an implementation of this primitive?

You will have to provide your own.  There is code for the x86-linux lock 
in the libc/sys/linux/machine/i386 directory.  Are we talking about an 
existing newlib platform or something new?

> * Are they hardware's dependant? (by exemple to use a primitive test and
> set)
>

Yes, it is hardware dependent.  If you have an atomic test and set insn 
or something similar, it is reasonably straightforward.  If there is no 
hardware support you will have to resort to some form of spin-lock.

-- Jeff J.