From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <50e939a08541d86375a5c6d79f118c91@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Got thread experience?
Date: Thu, 25 Oct 2007 17:35:56 -0400
From: Sape Mullender <sape@plan9.bell-labs.com>
In-Reply-To: <47210127.8080107@gmail.com>
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> So, those with experience with threading implementations on weird
> real-time or embedded operating systems:
> 
> Have you ever ran into a thread implementation where two threads
> could *not* directly access each other's .bss (or equiv)/heap?
> 
> i.e. have you ever encountered a scenario where sibling threads
> actually had completely separate sets of page tables?

Plan 9 distinguishes between threads and procs.  Procs are Plan 9
processes and can therefore have address spaces different from other
processes.  Usually, in threaded applications, the proc address
spaces only differ in the stack.

However, we have real-time embedded applications where some procs
map in memory segments that can be used to access certain peripherals.
In such applications procs do have different address spaces.  But they
are only somewhat different, certainly not as different as indicated
above.

	sape