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Leon mode in eCos
- From: "Michele Portolan" <michele dot Portolan at imag dot fr>
- To: <ecos-discuss at sources dot redhat dot com>
- Date: Thu, 1 Apr 2004 15:51:07 +0200
- Subject: [ECOS] Leon mode in eCos
Hi, I am working on eCos on Leon and I have a few questions about
user/supervisor modes: how are they used inside that OS?
I usually thought that in any OS threads where executed in user mode (S=0 in
PSR register), while all kernel function like scheduling where in supervisor
mode (S=1). Or, at least, that is what I have been taught.
Anyway debugging with cygwin/ddd on the "twothreads" example (two threads
are runned with the scheduler) I always find S=1. both in the kernel (I put
a breakpoint just before context-switch) and in the threads (breakpoints
during execution).
Can I safely assume that the processor is always in supervisor mode?
Thanks,
Michele
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