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<div class="moz-cite-prefix">Hi Bjorn,<br>
<br>
There actually was a port of Barrelfish to the Beehive
architecture, which does not have an MMU. That port is now
historical and the code removed from the tree. The last release to
support it was 2011-11-10
(<a class="moz-txt-link-freetext" href="http://hg.barrelfish.org/barrelfish/rev/256f62218262">http://hg.barrelfish.org/barrelfish/rev/256f62218262</a>) and you
should be able to look there for hints on how to do a port to an
architecture without an MMU.<br>
<br>
Have fun!<br>
Simon<br>
<br>
On 13-08-26 09:17 AM, Bjørn Christian Seime wrote:<br>
</div>
<blockquote
cite="mid:BAD0A799-9DA9-4F59-B467-0AA6D95D06E1@gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">Hi! </span></div>
<br style="font-weight: bold; ">
<span style="font-size: 15px; font-family: Arial; vertical-align:
baseline; white-space: pre-wrap; "></span>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">We are two Master students from NTNU
(Norwegian University of Science and Technology) currently
working on a project in which we are to implement a minimal
operating system for a simple, experimental architecture[1],
preferably by porting Barrelfish. The architecture consists of
multiple Amber[2] cores connected in a tile-based
architecture. These cores are fairly simple; specifically,
they do not have an MMU, or any other hardware mechanisms
available for implementing virtual memory or memory
protection. The amount of memory is also fairly limited
(around 32MB), and there is no hard drive available either to
use as backing storage. </span></div>
<br style="font-weight: bold; ">
<span style="font-size: 15px; font-family: Arial; vertical-align:
baseline; white-space: pre-wrap; "></span>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">In many ways, the architecture seems
like a good fit for the multikernel approach used in
Barrelfish. However, as (to our knowledge) all the existing
ports of Barrelfish have virtual memory support, we are
worried as to whether some part of the operating system is
relying on its existence. We have read some previous theses on
porting Barrelfish to new architectures[3,4,5]; all of them
consider the challenges of implementing virtual memory, but
none discuss the reliance on it of other parts of the system.
As this is something we might not discover until a late stage
in the porting process, we figured that consulting the experts
who might immediately know of problems we would encounter
would be a pragmatic approach. Can you think of any issues
which would prohibit porting Barrelfish to this MMU-less
environment?</span></div>
<br style="font-weight: bold; ">
<span style="font-size: 15px; font-family: Arial; vertical-align:
baseline; white-space: pre-wrap; "></span>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">Sincerely,</span></div>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">Bjorn C. Seime and Benjamin Bjornseth</span></div>
<br style="font-weight: bold; ">
<span style="font-size: 15px; font-family: Arial; vertical-align:
baseline; white-space: pre-wrap; "></span>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">[1]: </span><a
moz-do-not-send="true"
href="http://research.idi.ntnu.no/eecs/shmac"
style="text-decoration: none; "><span style="font-size: 15px;
font-family: Arial; color: rgb(17, 85, 204); font-weight:
normal; text-decoration: underline; vertical-align:
baseline; white-space: pre-wrap; ">http://research.idi.ntnu.no/eecs/shmac</span></a><span
style="font-size: 15px; font-family: Arial; font-weight:
normal; vertical-align: baseline; white-space: pre-wrap; "></span></div>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">[2]: </span><a
moz-do-not-send="true"
href="http://en.wikipedia.org/wiki/Amber_%28processor_core%29"
style="text-decoration: none; "><span style="font-size: 15px;
font-family: Arial; color: rgb(17, 85, 204); font-weight:
normal; text-decoration: underline; vertical-align:
baseline; white-space: pre-wrap; ">http://en.wikipedia.org/wiki/Amber_(processor_core)</span></a><span
style="font-size: 15px; font-family: Arial; font-weight:
normal; vertical-align: baseline; white-space: pre-wrap; "></span></div>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">[3]: </span><a
moz-do-not-send="true"
href="http://www.diva-portal.org/smash/get/diva2:635212/FULLTEXT01.pdf"
style="text-decoration: none; "><span style="font-size: 15px;
font-family: Arial; color: rgb(17, 85, 204); font-weight:
normal; text-decoration: underline; vertical-align:
baseline; white-space: pre-wrap; ">http://www.diva-portal.org/smash/get/diva2:635212/FULLTEXT01.pdf</span><span
style="font-size: 15px; font-family: Arial; color: rgb(0, 0,
0); font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; "></span></a></div>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">[4]: </span><a
moz-do-not-send="true"
href="http://www.barrelfish.org/scheidegger-bachelor-netronome.pdf%E2%80%8E"
style="text-decoration: none; "><span style="font-size: 15px;
font-family: Arial; color: rgb(17, 85, 204); font-weight:
normal; text-decoration: underline; vertical-align:
baseline; white-space: pre-wrap; ">www.barrelfish.org/scheidegger-bachelor-netronome.pdf‎</span></a><span
style="font-size: 15px; font-family: Arial; font-weight:
normal; vertical-align: baseline; white-space: pre-wrap; "></span></div>
<div style="font-weight: bold; line-height: 1.15; margin-top: 0pt;
margin-bottom: 0pt; "><span style="font-size: 15px; font-family:
Arial; font-weight: normal; vertical-align: baseline;
white-space: pre-wrap; ">[5]: </span><span
style="text-decoration: underline; font-size: 15px;
font-family: Arial; color: rgb(17, 85, 204); font-weight:
normal; vertical-align: baseline; white-space: pre-wrap; "><a
moz-do-not-send="true"
href="http://www.barrelfish.org/hitz-bachelor-multicore-arm.pdf%E2%80%8E"
style="text-decoration: none; ">www.barrelfish.org/hitz-bachelor-multicore-arm.pdf‎</a></span></div>
<div><br>
</div>
<br>
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