Richard Pennington | 3 Jan 11:51 2015

Anyone still around?

Hi,

I know this list was been quiet for some time, but I thought that there 
might still be some interest is some Prex related work that I've been doing.
I have been developing a cross compilation tool chain based on 
clang/LLVM for ARM, Mips, PowerPC, and x86 processors. I call the 
project ELLCC (pronounced "elk") http://ellcc.org
The project currently fully supports C and C++ compilation for all the 
target processors running Linux. I also want to support bare metal 
development on all the targets, so I started a sub-project called ELK 
("Embedded Little Kernel") for that purpose. The goal of ELK is to use 
the same C/C++ run-time libraries (using the BSD or BSD-like licensed 
libc++, musl, and compiler-rt) for both the Linux and ELK environments 
and it has been coming along very well.
About a month and a half ago I decided I wanted to add file system 
support to ELK and after some googling I stumbled across Prex. I was 
very impressed by the design and clarity of the code, so I decided to 
borrow some of it for my ELK project. I won't go into too much detail 
here, but here's what I've done so far:
* Incorporated the Prex file system, console/tty and VM code (both MMU 
and non-MMU).
* Cleaned up a few minor design issues (e.g. vnode locks can be read 
only or R/W, no schedule_lock(), finer grained locking)
This week I added networking support by incorporating the LwIP TCP/IP 
stack. (It currently can only communicate on 127.0.0.1 because I haven't 
added Ethernet drivers yet.)

The current incarnation of ELK only runs on ARM. I'd like to add the 
glue for the other targets soon as time allows.

(Continue reading)

Paul Dufresne | 19 Mar 05:13 2014
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prex 0.9 x86-pc compiles but does not boot under gcc 4.8.2 (works under 4.2.4)

unchanged version 0.9.0 was compiling fine on gcc 4.8.2.
But when I was $mcopy prex-0.9.0/prexos a:\prexos (choosing overwrite)
with /etc/mtools.conf having drive a: file="/home/paul/prex-0.8.0,i386-pc.img"
then $qemu-kvm -fda ./prex-0.8.0.i386-pc.img -localtime
messages was going very fast, but was having time to read Booting
Prexos, then blackscreen.

So I did manually apply:
http://www.eighty-twenty.org/index.cgi/tech/prex-bug-20110317.html
did not use -p option of patch... had to manually apply (not used to
apply patches).

But it did not help.

Then I tried to recompile 0.8.1 but had problem:
first configure had not --target=pc-x86 was not working
so I only ./configure, but then make:
.../boot/common/debug.c:50: undefined reference to '__builtin_stdarg_start'

So I begin trying older gcc (4.2.4) but no better results.

So I then compiled back 0.9.0 (make clean; make)
And this time after the mcopy command, qemu worked!
And this must be really 0.9.0 because I now can play tetris, and was
not having tetris in 0.8.0.

So it appears that 0.9.0 build fine with gcc 4.8.2 but then does not boot.
Builds fine, and boots with gcc 4.2.4.
Did not (yet) tested gcc versions between 4.2.4 and 4.8.2.

(Continue reading)

David Given | 22 May 19:24 2013

Current VCS?

I have a hardware project for which I need a simple operating system
that works without an MMU, and Prex would seem to be a decent candidate.
While I'm aware that the Sourceforge site isn't receiving updates any
more, has anyone been doing any work on Prex and happen to have a DVCS
site with updates in it?

-- 
┌─── dg@cowlark.com ─────
http://www.cowlark.com ─────
│
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Gustavo Luiz Pasqualini | 15 Mar 01:44 2013
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Contact - Prex

Hello,

I am a student of Masters in Mechatronics by IFSC (Federal Institute of Science and Technology).

My research includes testing different RTOS (hard and soft) in order to determine which best responds to
certain events of mechatronic systems and give a comparative result of these activities and performance
time control and supervision.

The ideia is to load in the same hardware these compatibles RTOS. The plataform is the Kit Luminary
lm3s8962(Stellaris Arm Cortex - Texas) and after make the tests.

My doubt is whether the license of the RTOS that you develop, and allows comparative study such as this
survey will become part of the library and maybe future projects with public access.

Do you have any material / documentation / articles / monographies about this RTOS for i attach in my work?

Best Regards,
Gustavo
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alireza ghassemi | 22 Nov 05:10 2011
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(no subject)

http://dnfhw.com/dF8SbpvO3qHUTsB/templets/hbbbs.htm

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Tony Garnock-Jones | 30 May 13:38 2011

Exception handling bug

Hi all,

Prex on x86 has a bug in its exception handler. I've tried a couple of 
times to post this to the list, but each time it has been held back, so 
this time I'll try linking to a blog post I wrote about it instead:
http://www.eighty-twenty.org/index.cgi/tech/prex-bug-20110317.html

Regards,
   Tony

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Elinam Hini | 28 May 22:39 2011

Arm based access point

Hey Guys,
What is the status of Prex, is it stable? I would like to use Prex to develop access points for a wireless
sensor node project. I am targeting technologic's TS-7552 and TS 7300 single board computers. The are ARM based.

Thanks,
Eli
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Andrew Dennison | 12 Feb 05:45 2011
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Re: Educational use?

Replying to the list too...

On 12 February 2011 14:48, Peter Desnoyers <pjd <at> ccs.neu.edu> wrote:
> On 02/11/2011 07:27 PM, Andrew Dennison wrote:
>> On 11 February 2011 14:46, Peter Desnoyers <pjd <at> ccs.neu.edu> wrote:
>>> I'm  using Prex in an operating systems class this term, and was
>>> wondering if anyone else had tried this.
>>>
>>> I was also wondering whether the project has gone dead, as there are
>>> very few messages on this list since last July.
>>
>> This sounds like a very good use of Prex, as it has a fairly clean
>> structure and good abstraction of the architecture specific
>> components.
>
> Yes, as a matter of fact my class just came up with a very good list of
> possible projects this morning.
>
> By the way, do you know if anyone has a good solution to debugging
> user-space code on MMU systems? It should be straightforward on NOMMU,
> but gdb e.g. through the QEMU stub is justifiably confused by the re-use
> of the same address space in every task. If there isn't anything, we
> have some ideas for a gdb stub that could be linked with an executable,
> and a couple of extensions to sys_debug.

Normally you would maintain a debug context for each process, and swap
the debug context as part of the task switch - the OS needs to
cooperate in this exercise. I've done this for some simple debug
support using the hardware debug support in our target processor: I'll
setup a gdb stub one day.
(Continue reading)

Andrew Dennison | 12 Feb 01:29 2011
Picon

Fwd: Educational use?

On 11 February 2011 14:46, Peter Desnoyers <pjd <at> ccs.neu.edu> wrote:
> I'm  using Prex in an operating systems class this term, and was
> wondering if anyone else had tried this.
>
> I was also wondering whether the project has gone dead, as there are
> very few messages on this list since last July.

This sounds like a very good use of Prex, as it has a fairly clean
structure and good abstraction of the architecture specific
components.

The Prex mailing list has always been quiet, but there seem to be a
few of us lurking and ready to join in whenever some discussion
starts.

For the most part we're been just _using_ Prex for the last 6 months
or so, it is now nice and stable so our efforts have all been focused
on our product rather than more enhancements to Prex. Unfortunately I
can't comment on Prex 0.9, as I haven't yet found the time to merge
our changes with the latest release.

We haven't heard from Kohsuke for a while but I'm sure he is working
away adding some interesting features.

Andrew

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Peter Desnoyers | 11 Feb 04:46 2011

Educational use?

I'm  using Prex in an operating systems class this term, and was
wondering if anyone else had tried this.

I was also wondering whether the project has gone dead, as there are
very few messages on this list since last July.

--

-- 
.....................................................................
 Peter Desnoyers                                  pjd <at> ccs.neu.edu
 Northeastern Computer & Information Science

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bifferos | 10 Jan 12:17 2011
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ne2000 ethernet driver

Hi all,

I just thought I'd mention I have ne2000 support added to my own small
IP stack in another project and thought it might be useful for Prex.  
I remember some time in a post long ago someone mentioning they'd be
prepared to port an IP stack to Prex so long as someone else wrote 
a driver.  I started looking at which was the simplest driver in 
Linux (ne2k), then removed all the parts that aren't needed for 
the Qemu emulated version by inspecting the Qemu sources, also 
removed interrupt support so you have to poll it.

All I've tested is that I can use the driver to do DHCP query and get an 
IP address back from Qemu, there could be plenty of bugs, but it's 
certainly helping me with my work, so thought I'd share it here.

The driver is C++ but in a C style, see attachment at the bottom of
the page:
http://sites.google.com/site/bifferboard/Home/rtos/grub-configuration-on-floppy-disk

Hopefully it's a trivial job to convert to C.

best regards,
Biff.

PS:  Consider the code to be in the public domain!

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