Porting ELKS

Porting ELKS

[Raghavan]

Hi,

I am intending to port ELKS on to Analog Devices's  Blackfin DSP Processor.

I am having a couple of questions

(1) Does ELKS take advantage of the MMU facility of the x86 Systems ?. I ask
this because the Blackfin does not.

(2) What would be a good strategy to start the porting exercise ? Any
previous porting lessons would help.

Bye,
Raghavan V

Re: Porting ELKS

[Alan Cox]

On Gwe, 2003-07-18 at 11:57, Raghavan wrote:
> (1) Does ELKS take advantage of the MMU facility of the x86 Systems ?. I ask
> this because the Blackfin does not.

ELKS uses the segmentation on the 8086 CPU.

> (2) What would be a good strategy to start the porting exercise ? Any
> previous porting lessons would help.

It depends what you need the OS for and what size you want. eCOS is
probably the better embedded OS and there is mmuless support in the 2.6
development Linux kernels if you want the full thing.

Re: Porting ELKS

[Syed Faisal Akber]

Hi Raghavan,

I think that porting ELKS to the Blackfin is a waste of time.  ELKS is
written to take advantage of 8086 processor quirks.  The Blackfin (or MSA)
architecture is quite a bit different.

(1) The Blackfin does not have an TLB based MMU.  You cannot use Linux,
but you can use uClinux.  ELKS is similar to uClinux but the memory models
are very different.

(2) You may want to start using uClinux.  There already exists a port for
Blackfin.  You will probably have to contact Analog Devices to get more
information regarding this.

Regards,
Faisal

On Fri, 18 Jul 2003, Raghavan wrote:

> Hi,
>
> I am intending to port ELKS on to Analog Devices's  Blackfin DSP Processor.
>
> I am having a couple of questions
>
> (1) Does ELKS take advantage of the MMU facility of the x86 Systems ?. I ask
> this because the Blackfin does not.
>
> (2) What would be a good strategy to start the porting exercise ? Any
> previous porting lessons would help.
>
> Bye,
> Raghavan V
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: Porting ELKS

[Raghavan]

Syed et al,

Thanks for the Info.

Let me explain the background a little bit as to why I am exploring this. It
will give you a better picture.

I wanted to have a few applications on Blackfin DSP. Let's say like web
server, rtsp server etc...

I pick up any free application on the Web , they all run on POSIX compliant
OS like LINUX.
Porting a full fledged LINUX is really a tough job ( ?) , so I thought ELKS
was a good option and started looking at it.

ucLinux seemed a good Idea, I checked with ADI, the answer I got is "The
ucLinux port is on the way , but it could take a while .."

I need to have a OS on the BLACKFIN quickly ..so that I get the applications
on it ..and hence I was thinking ELKS ...;

Are you saying ELKS would be inefficient on the DSP Processor ..or is it
that porting ELKS on Blackfin be like a total rewrite ?

Is eCOS port feasible like say in a 3-4 months time frame ? Is eCOS POSIX
compliant ..so that we can get any application compile & run on it easily ?

Bye,
Raghavan V





----- Original Message -----
From: "Syed Faisal Akber" <faisal.akber@utoronto.ca>
To: "Raghavan" <raghavan.viswanathan@wipro.com>
Cc: <Linux-8086@Vger.Kernel.Org>
Sent: Monday, July 21, 2003 1:12 AM
Subject: Re: Porting ELKS


> Hi Raghavan,
>
> I think that porting ELKS to the Blackfin is a waste of time.  ELKS is
> written to take advantage of 8086 processor quirks.  The Blackfin (or MSA)
> architecture is quite a bit different.
>
> (1) The Blackfin does not have an TLB based MMU.  You cannot use Linux,
> but you can use uClinux.  ELKS is similar to uClinux but the memory models
> are very different.
>
> (2) You may want to start using uClinux.  There already exists a port for
> Blackfin.  You will probably have to contact Analog Devices to get more
> information regarding this.
>
> Regards,
> Faisal
>
> On Fri, 18 Jul 2003, Raghavan wrote:
>
> > Hi,
> >
> > I am intending to port ELKS on to Analog Devices's  Blackfin DSP
Processor.
> >
> > I am having a couple of questions
> >
> > (1) Does ELKS take advantage of the MMU facility of the x86 Systems ?. I
ask
> > this because the Blackfin does not.
> >
> > (2) What would be a good strategy to start the porting exercise ? Any
> > previous porting lessons would help.
> >
> > Bye,
> > Raghavan V
> >
> >
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>

RE: Porting ELKS

[Riley Williams]

Hi.

The major part of any port would be to port GCC to the selected
processor (which means writing the GCC backend for that processor)
so it can compile the relevant source code. Once you've done that,
you've cracked 90% of porting either Linux or ELKS across since
GCC will compile that much of either for you.

 > Let me explain the background a little bit as to why I am
 > exploring this. It will give you a better picture.
 >
 > I wanted to have a few applications on Blackfin DSP. Let's
 > say like web server, rtsp server etc...
 >
 > I pick up any free application on the Web , they all run on
 > POSIX compliant OS like LINUX. Porting a full fledged LINUX
 > is really a tough job ( ?) , so I thought ELKS was a good
 > option and started looking at it.
 >
 > ucLinux seemed a good Idea, I checked with ADI, the answer I
 > got is "The ucLinux port is on the way , but it could take a
 > while .."
 >
 > I need to have a OS on the BLACKFIN quickly ..so that I get
 > the applications on it ..and hence I was thinking ELKS ...;
 >
 > Are you saying ELKS would be inefficient on the DSP Processor
 > ... or is it that porting ELKS on Blackfin be like a total
 > rewrite ?

With either ELKS or Linux, the bulk of the porting job would be
with getting GCC to compile for that processor. You'd then be
faced with rewriting the assembly language parts of whatever OS
you wished to port, and that would essentially be the port done.

 > Is eCOS port feasible like say in a 3-4 months time frame ?
 > Is eCOS POSIX compliant ... so that we can get any application
 > compile & run on it easily ?

I can't personally comment on eCOS as I know nothing about it,
sorry.

Best wishes from Riley.
---
 * Nothing as pretty as a smile, nothing as ugly as a frown.

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Checked by AVG anti-virus system (http://www.grisoft.com).
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Re: Porting ELKS

[Syed Faisal Akber]

Porting ELKS to Blackfin would be a complete and total rewrite of the
memory management.  The segmented memory model doesn't suit the Blackfin
processor well and would probably degrade the performance on that
processor.

eCOS is POSIX compliant.

On Mon, 21 Jul 2003, Raghavan wrote:

>
> Are you saying ELKS would be inefficient on the DSP Processor ..or is it
> that porting ELKS on Blackfin be like a total rewrite ?


>
> Is eCOS port feasible like say in a 3-4 months time frame ? Is eCOS POSIX
> compliant ..so that we can get any application compile & run on it easily ?
>
> Bye,
> Raghavan V
>
>
>
>
>
> ----- Original Message -----
> From: "Syed Faisal Akber" <faisal.akber@utoronto.ca>
> To: "Raghavan" <raghavan.viswanathan@wipro.com>
> Cc: <Linux-8086@Vger.Kernel.Org>
> Sent: Monday, July 21, 2003 1:12 AM
> Subject: Re: Porting ELKS
>
>
> > Hi Raghavan,
> >
> > I think that porting ELKS to the Blackfin is a waste of time.  ELKS is
> > written to take advantage of 8086 processor quirks.  The Blackfin (or MSA)
> > architecture is quite a bit different.
> >
> > (1) The Blackfin does not have an TLB based MMU.  You cannot use Linux,
> > but you can use uClinux.  ELKS is similar to uClinux but the memory models
> > are very different.
> >
> > (2) You may want to start using uClinux.  There already exists a port for
> > Blackfin.  You will probably have to contact Analog Devices to get more
> > information regarding this.
> >
> > Regards,
> > Faisal
> >
> > On Fri, 18 Jul 2003, Raghavan wrote:
> >
> > > Hi,
> > >
> > > I am intending to port ELKS on to Analog Devices's  Blackfin DSP
> Processor.
> > >
> > > I am having a couple of questions
> > >
> > > (1) Does ELKS take advantage of the MMU facility of the x86 Systems ?. I
> ask
> > > this because the Blackfin does not.
> > >
> > > (2) What would be a good strategy to start the porting exercise ? Any
> > > previous porting lessons would help.
> > >
> > > Bye,
> > > Raghavan V
> > >
> > >
> > > -
> > > To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > >
> >
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

RE: Porting ELKS

[Syed Faisal Akber]

The GCC port does exist, but as with the uClinux kernel you need to
contact Analog Devices to get it.

Faisal

On Mon, 21 Jul 2003, Riley Williams wrote:

> Hi.
>
> The major part of any port would be to port GCC to the selected
> processor (which means writing the GCC backend for that processor)
> so it can compile the relevant source code. Once you've done that,
> you've cracked 90% of porting either Linux or ELKS across since
> GCC will compile that much of either for you.
>
>  > Let me explain the background a little bit as to why I am
>  > exploring this. It will give you a better picture.
>  >
>  > I wanted to have a few applications on Blackfin DSP. Let's
>  > say like web server, rtsp server etc...
>  >
>  > I pick up any free application on the Web , they all run on
>  > POSIX compliant OS like LINUX. Porting a full fledged LINUX
>  > is really a tough job ( ?) , so I thought ELKS was a good
>  > option and started looking at it.
>  >
>  > ucLinux seemed a good Idea, I checked with ADI, the answer I
>  > got is "The ucLinux port is on the way , but it could take a
>  > while .."
>  >
>  > I need to have a OS on the BLACKFIN quickly ..so that I get
>  > the applications on it ..and hence I was thinking ELKS ...;
>  >
>  > Are you saying ELKS would be inefficient on the DSP Processor
>  > ... or is it that porting ELKS on Blackfin be like a total
>  > rewrite ?
>
> With either ELKS or Linux, the bulk of the porting job would be
> with getting GCC to compile for that processor. You'd then be
> faced with rewriting the assembly language parts of whatever OS
> you wished to port, and that would essentially be the port done.
>
>  > Is eCOS port feasible like say in a 3-4 months time frame ?
>  > Is eCOS POSIX compliant ... so that we can get any application
>  > compile & run on it easily ?
>
> I can't personally comment on eCOS as I know nothing about it,
> sorry.
>
> Best wishes from Riley.
> ---
>  * Nothing as pretty as a smile, nothing as ugly as a frown.
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.502 / Virus Database: 300 - Release Date: 18-Jul-2003
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: Porting ELKS

[Raghavan]

Fasal,

Thanks very much for the reply.

If I understand you correctly, we "can" have a port of ELKS as is without
change in Memory model , but it
will possibly be pedestrian.

I took a look at eCOS , but it looks like a nice full fledged OS with
excellent features. Porting it might be
a difficult task might be like an Year or so ...

I am inclined towards ELKS because I can possibly have a port like in 3 to 4
months ...
My priority is really to have applications running on Blackfin ASAP.

Also, why do we need to have gcc ported ?
Cant I use the native compiler provided by ADI guys for the Blackfin
Processor ?
Yeah..I need to tweak the compiler options to the respective equivalents on
Blackfin Compiler ..; I am not seeing anything else ...
Am I missing something ?

Am I looking too optimistic to assume a 'as is' port of ELKS to Blackfin
in 3 to 4 months ? I was thinking of taking Memory management after I have a
'working' version of  ELKS ...

Does this sound reasonable ?

Bye,
Raghavan V

----- Original Message -----
From: "Syed Faisal Akber" <faisal.akber@utoronto.ca>
To: "Raghavan" <raghavan.viswanathan@wipro.com>
Cc: <Linux-8086@Vger.Kernel.Org>
Sent: Monday, July 21, 2003 10:18 PM
Subject: Re: Porting ELKS


> Porting ELKS to Blackfin would be a complete and total rewrite of the
> memory management.  The segmented memory model doesn't suit the Blackfin
> processor well and would probably degrade the performance on that
> processor.
>
> eCOS is POSIX compliant.
>
> On Mon, 21 Jul 2003, Raghavan wrote:
>
> >
> > Are you saying ELKS would be inefficient on the DSP Processor ..or is it
> > that porting ELKS on Blackfin be like a total rewrite ?
>
>
> >
> > Is eCOS port feasible like say in a 3-4 months time frame ? Is eCOS
POSIX
> > compliant ..so that we can get any application compile & run on it
easily ?
> >
> > Bye,
> > Raghavan V
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Syed Faisal Akber" <faisal.akber@utoronto.ca>
> > To: "Raghavan" <raghavan.viswanathan@wipro.com>
> > Cc: <Linux-8086@Vger.Kernel.Org>
> > Sent: Monday, July 21, 2003 1:12 AM
> > Subject: Re: Porting ELKS
> >
> >
> > > Hi Raghavan,
> > >
> > > I think that porting ELKS to the Blackfin is a waste of time.  ELKS is
> > > written to take advantage of 8086 processor quirks.  The Blackfin (or
MSA)
> > > architecture is quite a bit different.
> > >
> > > (1) The Blackfin does not have an TLB based MMU.  You cannot use
Linux,
> > > but you can use uClinux.  ELKS is similar to uClinux but the memory
models
> > > are very different.
> > >
> > > (2) You may want to start using uClinux.  There already exists a port
for
> > > Blackfin.  You will probably have to contact Analog Devices to get
more
> > > information regarding this.
> > >
> > > Regards,
> > > Faisal
> > >
> > > On Fri, 18 Jul 2003, Raghavan wrote:
> > >
> > > > Hi,
> > > >
> > > > I am intending to port ELKS on to Analog Devices's  Blackfin DSP
> > Processor.
> > > >
> > > > I am having a couple of questions
> > > >
> > > > (1) Does ELKS take advantage of the MMU facility of the x86 Systems
?. I
> > ask
> > > > this because the Blackfin does not.
> > > >
> > > > (2) What would be a good strategy to start the porting exercise ?
Any
> > > > previous porting lessons would help.
> > > >
> > > > Bye,
> > > > Raghavan V
> > > >
> > > >
> > > > -
> > > > To unsubscribe from this list: send the line "unsubscribe
linux-8086" in
> > > > the body of a message to majordomo@vger.kernel.org
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > >
> > >
> >
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-8086" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>

Re: Porting ELKS

[Syed Faisal Akber]

On Tue, 22 Jul 2003, Raghavan wrote:

> Fasal,
>
> Thanks very much for the reply.
>
> If I understand you correctly, we "can" have a port of ELKS as is without
> change in Memory model , but it
> will possibly be pedestrian.

No, you will have to make major changes in the way the memory and other
platform specific things are handled.

>
> I took a look at eCOS , but it looks like a nice full fledged OS with
> excellent features. Porting it might be
> a difficult task might be like an Year or so ...
>

Sounds about right if you are doing it alone with little knowledge of the
OS you are working on.

> I am inclined towards ELKS because I can possibly have a port like in 3 to 4
> months ...
> My priority is really to have applications running on Blackfin ASAP.
>

It would take longer to do this

> Also, why do we need to have gcc ported ?

Most of the opensource OS's require gcc as a compiler.  This is because
they take advantage of its special features.  Also GCC is more likely to
conform to C language standards than compilers provided by chip
manufacturers.

> Cant I use the native compiler provided by ADI guys for the Blackfin
> Processor ?

If you like but it would be more difficult to use and you would have to
port much more of the code to support the compiler.  I have used VisualDSP
for BLACKfin and found it to have many quirks.

> Yeah..I need to tweak the compiler options to the respective equivalents on
> Blackfin Compiler ..; I am not seeing anything else ...
> Am I missing something ?

The two compilers are by no means the same at all.  Using the commercial
compiler will cause you grief and cause your project timelines to be
extended 2 to 3 fold.

>
> Am I looking too optimistic to assume a 'as is' port of ELKS to Blackfin
> in 3 to 4 months ? I was thinking of taking Memory management after I have a
> 'working' version of  ELKS ...
>

An AS IS port will not work for you.


> Does this sound reasonable ?
>

The eCOS does sound reasonable, but I think using ELKS would be in the
same realm.  The regular Linux 2.6 kernel now has full support of MMU-less
systems.  You might want to look at it as an alternative.

Regards,
Faisal