I put rtl_no_interrupts and rtl_restore_interrupts in the newer versions
of RTLinux to simplify and optimize the interface and to make a clear
distinction between "no_interrupts" and "atomic". Linux, through heroic
efforts, has extended the cli/sti semantics to smp machines. RTLinux needs
to make programmers aware of the difference since there can be significant
timing differences: "no_interrupts" is a deterministic operation taking
a few cycles, while ensuring that only one task is in a critical section
may involve a spin loop. rt_ipc should be changed to reflect the new names.
If you look in the rtl_fifo code you will see how to make things smp safe.
Also, it might should be rtl_ipc. I've been changing the prefixes gradually
because rt_ is used in linux code for both the cmos clock and tcp code.
On Tue, Mar 23, 1999 at 09:05:21AM -0600, Pierre Cloutier wrote:
>
> Hi:
>
> rt_ipc uses r_save_flags(s) r_cli() and r_restore_flags(s) to isolate
> critical code.
>
> rtl_sync.h provides rtl_no_interrupts(s) and rtl_restore_interrupts(s)
> to do the same thing.
>
> Could someone explain the difference? I suspect the macros are not in
> rtl_synch.h just for fun.
>
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