RE: [ECOS] Simple Redboot Q's

RE: [ECOS] Simple Redboot Q's

[Matt Sartori]

-----Original Message-----
From: Gary Thomas [mailto:gary@mlbassoc.com] 
Sent: 26 July 2005 16:00
To: Matt Sartori
Cc: Andrew Lunn; eCos Discussion
Subject: RE: [ECOS] Simple Redboot Q's


>Unless your code is position independent (or very smart), this is most
certainly your problem.

Ok, good. That's something I can look at then. 
Redboot, despite being a ROM build, says it's using RAM from 0x20000000
to 0x20005b68, so I've made
my linker script place CODE at 0x20005b68 and DATA at 0x20008000 (with a
total RAM range of 0x10000).
This, I take it, is only significant if I load it as an elf. And, again
if I understand correctly, when loaded as -r it just goes where I put
it.
Obviously there's still something I don't understand correctly 'cause it
doesn't work. 
Is the entry point usually different from the fist address?
 
>What's wrong with using eCos to help you build your program?

Nothing as such, but a) I'm trying to keep it as simple as possible, b)
linking against anything adds to the size and, since I've yet to write
the flash drivers, I've only got 64K of memory (less what Redboot is
using up) for my program, c) I was looking to use Redboot only as a
bootloader to update my custom software and run it.

>n.b. this is an eCos list, so we're oriented that way :-)

Understandibly so. It's a very impressive system and one I'm hoping to
eventually grok.

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Re: [ECOS] Simple Redboot Q's

[Andrew Lunn]

> >Unless your code is position independent (or very smart), this is most
> certainly your problem.
> 
> Ok, good. That's something I can look at then. 
> Redboot, despite being a ROM build, says it's using RAM from 0x20000000
> to 0x20005b68, so I've made
> my linker script place CODE at 0x20005b68 and DATA at 0x20008000 (with a
> total RAM range of 0x10000).
> This, I take it, is only significant if I load it as an elf. And, again
> if I understand correctly, when loaded as -r it just goes where I put
> it.
> Obviously there's still something I don't understand correctly 'cause it
> doesn't work. 

Find out what position independant means. The comments above make me
think you understand what this means.

        Andrew

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RE: [ECOS] Simple Redboot Q's

[Matt Sartori]

In fact it turns out that most of the code I'm trying to run is fine
(and position independent). 
Where it falls down is in the interrupt setup which isn't position
independent. 
My code (wrongly) assumes that the interrupt vector is pointing to it's
own ISRs whereas interrupts are in fact being handled by Redboot.
Fortunately I had written the setup code for interrupts within Redboot
and put a bit of code to flash an led whenever the hal_IRQ_handler fun
was called or it would have taken me ages to realise what was going on.
I guess I have two choices here; If I want to make use of interrupts in
Redboot (not sure if flash needs them) I'd have to pass them on to my
own app's ISRs when appropriate. If I don't need Redboot interrupts then
I could just not set them up in Redboot? I couldn't find a switch in the
configtool, so that's probably the way to do it.

Many thanks to Andrew and Gary who have had the patience to prod me in
the right directions.

m@

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: 26 July 2005 18:22
To: Matt Sartori
Cc: eCos Discussion
Subject: Re: [ECOS] Simple Redboot Q's


On Tue, Jul 26, 2005 at 06:03:51PM +0100, Matt Sartori wrote:
> Yes, that all the jumps and references within the code are relative, 
> not absolute.

Nope. eCos is position dependant. ie you have to load it where it
expects to be loaded. Otherwise it crashes and burns.

> I think what I'm not quite understanding is what the load does.
> I would expect the loading of an elf to involve the interpretation of
> the file as to where to put it (and probably other stuff), however
> loading an elf explicitly to a location (with -b) doesn't make logical
> sense to me since the elf already knows where it wants to go. 

Correct. You should not tell the loader where to put the image. You only
need this for raw binaries. That format does not contain the position
information so you have to tell it.

> Equally baffling to me is when I load a .bin to an explicit location 
> then I can't just run it from that location.
>
> Only when I load the .bin into the same memory location as what I've 
> put in the binary's linker script does it work

Thats the position independant stuff again... You code appears not to be
position independant. It contains absolute addresses, not relative
addresses. Hence when its in the wrong place it crashes an burns.

If you want to be able to load your application to any random address
you need to make your application position independant. This can be
quite difficult, so most applications don't do it.

        Andrew

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Re: [ECOS] Simple Redboot Q's

[Andrew Lunn]

On Tue, Jul 26, 2005 at 06:03:51PM +0100, Matt Sartori wrote:
> Yes, that all the jumps and references within the code are relative, not
> absolute.

Nope. eCos is position dependant. ie you have to load it where it
expects to be loaded. Otherwise it crashes and burns.

> I think what I'm not quite understanding is what the load does. 
> I would expect the loading of an elf to involve the interpretation of
> the file as to where to put it (and probably other stuff), however
> loading an elf explicitly to a location (with -b) doesn't make logical
> sense to me since the elf already knows where it wants to go. 

Correct. You should not tell the loader where to put the image. You
only need this for raw binaries. That format does not contain the
position information so you have to tell it.

> Equally baffling to me is when I load a .bin to an explicit location
> then I can't just run it from that location.
>
> Only when I load the .bin into the same memory location as what I've put
> in the binary's linker script does it work

Thats the position independant stuff again... You code appears not to
be position independant. It contains absolute addresses, not relative
addresses. Hence when its in the wrong place it crashes an burns.

If you want to be able to load your application to any random address
you need to make your application position independant. This can be
quite difficult, so most applications don't do it.

        Andrew

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RE: [ECOS] Simple Redboot Q's

[Matt Sartori]

Yes, that all the jumps and references within the code are relative, not
absolute.
I think what I'm not quite understanding is what the load does. 
I would expect the loading of an elf to involve the interpretation of
the file as to where to put it (and probably other stuff), however
loading an elf explicitly to a location (with -b) doesn't make logical
sense to me since the elf already knows where it wants to go. 
Equally baffling to me is when I load a .bin to an explicit location
then I can't just run it from that location.
Only when I load the .bin into the same memory location as what I've put
in the binary's linker script does it work (yes, I've finally managed to
get it to run my code :) even if not quite sure why).

I apologize if this is basic stuff.

m@

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: 26 July 2005 17:30
To: Matt Sartori
Cc: eCos Discussion
Subject: Re: [ECOS] Simple Redboot Q's


> >Unless your code is position independent (or very smart), this is 
> >most
> certainly your problem.
> 
> Ok, good. That's something I can look at then.
> Redboot, despite being a ROM build, says it's using RAM from
0x20000000
> to 0x20005b68, so I've made
> my linker script place CODE at 0x20005b68 and DATA at 0x20008000 (with
a
> total RAM range of 0x10000).
> This, I take it, is only significant if I load it as an elf. And,
again
> if I understand correctly, when loaded as -r it just goes where I put
> it.
> Obviously there's still something I don't understand correctly 'cause
it
> doesn't work. 

Find out what position independant means. The comments above make me
think you understand what this means.

        Andrew

--------------------------------------------------------------------------------


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If you received this in error, please contact the sender or postmaster (postmaster@hanoverdisplays.com) and delete the material from any computer.

Although we routinely screen for viruses, addressees should check this e-mail and any attachment for viruses. We make no warranty as to absence of viruses in this e-mail or any attachments.

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RE: [ECOS] Simple Redboot Q's

[Gary Thomas]

On Tue, 2005-07-26 at 15:52 +0100, Matt Sartori wrote:
> Ok, that was also the command I initially thought I'd need. 
> However, using an elf (or even a binary) of code which I can flash
> directly to the board (using jtag and an ide) and run won't work if I
> load it into Redboot over the serial link and use go on it's initial
> location. I presume this may have something to do with the expected vs.
> actual location of the software? 

Unless your code is position independent (or very smart), this is
most certainly your problem.

> I'm not very experienced with this sort of thing (as you can probably
> tell) which is why I'd hoped that there were some (hello world type)
> examples that didn't involve linking against the ecos libs or loading up
> a linux image.

What's wrong with using eCos to help you build your program?

n.b. this is an eCos list, so we're oriented that way :-)

> 
> m@
> 
> -----Original Message-----
> From: Andrew Lunn [mailto:andrew@lunn.ch] 
> Sent: 26 July 2005 14:29
> To: Matt Sartori
> Cc: ecos-discuss@ecos.sourceware.org
> Subject: Re: [ECOS] Simple Redboot Q's
> 
> 
> On Tue, Jul 26, 2005 at 02:19:38PM +0100, Matt Sartori wrote:
> > Exec seems quite closely tied to linux (eg. When I enable the 
> > CYGBLD_BUILD_REDBOOT_WITH_EXEC it actually fails with some error in 
> > redboot_linux_exec.c). Can I run anything with Redboot using exec or 
> > is it looking for some kind of linux kernel image etc. ?
> 
> Exec is Linux specific
> 
> Use the go command for a more generic way of starting an arbitatry bit
> of code.
> 
> http://ecos.sourceware.org/docs-latest/redboot/executing-programs.html
> 
>         Andrew
> 
> --------------------------------------------------------------------------------
> 
> 
> The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
> 
> If you received this in error, please contact the sender or postmaster (postmaster@hanoverdisplays.com) and delete the material from any computer.
> 
> Although we routinely screen for viruses, addressees should check this e-mail and any attachment for viruses. We make no warranty as to absence of viruses in this e-mail or any attachments.
> 
> Our Company's email policy is to permit incidental personal use. If this email is of a personal nature, it must not be relied upon as expressing the views or opinions of the company.
> 
> Visit out website at www.hanoverdisplays.com
> 
> 

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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RE: [ECOS] Simple Redboot Q's

[Matt Sartori]

Ok, that was also the command I initially thought I'd need. 
However, using an elf (or even a binary) of code which I can flash
directly to the board (using jtag and an ide) and run won't work if I
load it into Redboot over the serial link and use go on it's initial
location. I presume this may have something to do with the expected vs.
actual location of the software? 
I'm not very experienced with this sort of thing (as you can probably
tell) which is why I'd hoped that there were some (hello world type)
examples that didn't involve linking against the ecos libs or loading up
a linux image.

m@

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: 26 July 2005 14:29
To: Matt Sartori
Cc: ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] Simple Redboot Q's


On Tue, Jul 26, 2005 at 02:19:38PM +0100, Matt Sartori wrote:
> Exec seems quite closely tied to linux (eg. When I enable the 
> CYGBLD_BUILD_REDBOOT_WITH_EXEC it actually fails with some error in 
> redboot_linux_exec.c). Can I run anything with Redboot using exec or 
> is it looking for some kind of linux kernel image etc. ?

Exec is Linux specific

Use the go command for a more generic way of starting an arbitatry bit
of code.

http://ecos.sourceware.org/docs-latest/redboot/executing-programs.html

        Andrew

--------------------------------------------------------------------------------


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If you received this in error, please contact the sender or postmaster (postmaster@hanoverdisplays.com) and delete the material from any computer.

Although we routinely screen for viruses, addressees should check this e-mail and any attachment for viruses. We make no warranty as to absence of viruses in this e-mail or any attachments.

Our Company's email policy is to permit incidental personal use. If this email is of a personal nature, it must not be relied upon as expressing the views or opinions of the company.

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RE: [ECOS] Simple Redboot Q's

[Gary Thomas]

On Tue, 2005-07-26 at 14:19 +0100, Matt Sartori wrote:
> Exec seems quite closely tied to linux (eg. When I enable the
> CYGBLD_BUILD_REDBOOT_WITH_EXEC it actually fails with some error in
> redboot_linux_exec.c). Can I run anything with Redboot using exec or is
> it looking for some kind of linux kernel image etc. ? 
> 

exec could be used to run most any image, but it is really designed
to run Linux.  In most cases (remember 'exec' is platform/architecture
specific), the command assumes certain operations before starting the
code: turning off the MMU, moving the program to a specific location
(on some architectures only), setting up some data structures to pass
to Linux, etc.  These are typically only useful if what you are running
is Linux (possibly other operating systems as well, e.g. FreeBSD)

> -----Original Message-----
> From: Andrew Lunn [mailto:andrew@lunn.ch] 
> Sent: 26 July 2005 12:05
> To: Matt Sartori
> Cc: ecos-discuss@ecos.sourceware.org
> Subject: Re: [ECOS] Simple Redboot Q's
> 
> 
> On Tue, Jul 26, 2005 at 11:16:15AM +0100, Matt Sartori wrote:
> > Does an application that is loaded and run by Redboot have to be 
> > linked against the eCos libraries?
> 
> No. eg your application could be Linux, which will simply take complete
> control of the hardware.
> 
> > What provisions would be necessary to make this work (e.g.. you 
> > obviously don't want your app to overwrite the rom area Redboot sits 
> > in) and are there any examples of this out there?
> 
> Look at how Linux is booted using RedBoot.
> 
>         Andrew
> 
> --------------------------------------------------------------------------------
> 
> 
> The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
> 
> If you received this in error, please contact the sender or postmaster (postmaster@hanoverdisplays.com) and delete the material from any computer.
> 
> Although we routinely screen for viruses, addressees should check this e-mail and any attachment for viruses. We make no warranty as to absence of viruses in this e-mail or any attachments.
> 
> Our Company's email policy is to permit incidental personal use. If this email is of a personal nature, it must not be relied upon as expressing the views or opinions of the company.
> 
> Visit out website at www.hanoverdisplays.com
> 
> 

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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Re: [ECOS] Simple Redboot Q's

[Andrew Lunn]

On Tue, Jul 26, 2005 at 02:19:38PM +0100, Matt Sartori wrote:
> Exec seems quite closely tied to linux (eg. When I enable the
> CYGBLD_BUILD_REDBOOT_WITH_EXEC it actually fails with some error in
> redboot_linux_exec.c). Can I run anything with Redboot using exec or is
> it looking for some kind of linux kernel image etc. ? 

Exec is Linux specific

Use the go command for a more generic way of starting an arbitatry bit
of code.

http://ecos.sourceware.org/docs-latest/redboot/executing-programs.html

        Andrew

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RE: [ECOS] Simple Redboot Q's

[Matt Sartori]

Exec seems quite closely tied to linux (eg. When I enable the
CYGBLD_BUILD_REDBOOT_WITH_EXEC it actually fails with some error in
redboot_linux_exec.c). Can I run anything with Redboot using exec or is
it looking for some kind of linux kernel image etc. ? 

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: 26 July 2005 12:05
To: Matt Sartori
Cc: ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] Simple Redboot Q's


On Tue, Jul 26, 2005 at 11:16:15AM +0100, Matt Sartori wrote:
> Does an application that is loaded and run by Redboot have to be 
> linked against the eCos libraries?

No. eg your application could be Linux, which will simply take complete
control of the hardware.

> What provisions would be necessary to make this work (e.g.. you 
> obviously don't want your app to overwrite the rom area Redboot sits 
> in) and are there any examples of this out there?

Look at how Linux is booted using RedBoot.

        Andrew

--------------------------------------------------------------------------------


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Re: [ECOS] Simple Redboot Q's

[Gary Thomas]

On Tue, 2005-07-26 at 13:05 +0200, Andrew Lunn wrote:
> On Tue, Jul 26, 2005 at 11:16:15AM +0100, Matt Sartori wrote:
> > Does an application that is loaded and run by Redboot have to be linked
> > against the eCos libraries?
> 
> No. eg your application could be Linux, which will simply take
> complete control of the hardware.
> 
> > What provisions would be necessary to make this work (e.g.. you
> > obviously don't want your app to overwrite the rom area Redboot sits in)
> > and are there any examples of this out there?
> 
> Look at how Linux is booted using RedBoot.

There is also pretty good support for building programs with
newlib.  In this case, newlib uses facilities (such as terminal
I/O, etc) exported by RedBoot.

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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Re: [ECOS] Simple Redboot Q's

[Andrew Lunn]

On Tue, Jul 26, 2005 at 11:16:15AM +0100, Matt Sartori wrote:
> Does an application that is loaded and run by Redboot have to be linked
> against the eCos libraries?

No. eg your application could be Linux, which will simply take
complete control of the hardware.

> What provisions would be necessary to make this work (e.g.. you
> obviously don't want your app to overwrite the rom area Redboot sits in)
> and are there any examples of this out there?

Look at how Linux is booted using RedBoot.

        Andrew

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[ECOS] Simple Redboot Q's

[Matt Sartori]

Does an application that is loaded and run by Redboot have to be linked
against the eCos libraries?
The examples in the "Embedded Software Development with eCos" book
suggests that you do but, aside from adding much to the size of the
application, you may just wish to run something that completely takes
over the hardware until the next reset.
The Redboot documentation says that this is the way it works but doesn't
give any examples.
What provisions would be necessary to make this work (e.g.. you
obviously don't want your app to overwrite the rom area Redboot sits in)
and are there any examples of this out there?
 
m@

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