[U-Boot-Users] Relocatable U-Boot

[U-Boot-Users] Relocatable U-Boot

[Josh Boyer]

Hi All,

My apologies if this has been discussed before, but I could not find
it in the archives I have.  I'm wondering if anyone has spent time on
making u-boot relocatable.

A handful of projects I have worked on use multiple copies of u-boot
stored in different locations of flash and a small assembly stub
determines which to boot.  Currently, to do that u-boot has to be
compiled two different times with different settings to accommodate
the different base addresses.

Is there a way to use a single build of u-boot which can be placed at
two different addresses in flash?  That seems to me that it would be a
useful general feature.

josh

[U-Boot-Users] Relocatable U-Boot

[Ulf Samuelsson]

> 
> A handful of projects I have worked on use multiple copies of u-boot
> stored in different locations of flash and a small assembly stub
> determines which to boot.  Currently, to do that u-boot has to be
> compiled two different times with different settings to accommodate
> the different base addresses.
> 
> Is there a way to use a single build of u-boot which can be placed at
> two different addresses in flash?  That seems to me that it would be a
> useful general feature.

If you copy your U-Boot to RAM, you can have multiple U-Boots
each linked to the same location.
You need a small utility which runs before U-Boot which
determines which version to use.

> 
> josh
> 


-- 
Best Regards,
Ulf Samuelsson
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[U-Boot-Users] Relocatable U-Boot

[Josh Boyer]

On 5/29/07, Ulf Samuelsson <ulf@atmel.com> wrote:
>
> >
> > A handful of projects I have worked on use multiple copies of u-boot
> > stored in different locations of flash and a small assembly stub
> > determines which to boot.  Currently, to do that u-boot has to be
> > compiled two different times with different settings to accommodate
> > the different base addresses.
> >
> > Is there a way to use a single build of u-boot which can be placed at
> > two different addresses in flash?  That seems to me that it would be a
> > useful general feature.
>
> If you copy your U-Boot to RAM, you can have multiple U-Boots
> each linked to the same location.
> You need a small utility which runs before U-Boot which
> determines which version to use.

Hm... yes.  Though I think that is more of a workaround than a truly
relocatable u-boot.

josh

[U-Boot-Users] Relocatable U-Boot

[Stefan Roese]

Hi Josh,

On Wednesday 30 May 2007, Josh Boyer wrote:
> On 5/29/07, Ulf Samuelsson <ulf@atmel.com> wrote:
> > > A handful of projects I have worked on use multiple copies of u-boot
> > > stored in different locations of flash and a small assembly stub
> > > determines which to boot.  Currently, to do that u-boot has to be
> > > compiled two different times with different settings to accommodate
> > > the different base addresses.
> > >
> > > Is there a way to use a single build of u-boot which can be placed at
> > > two different addresses in flash?  That seems to me that it would be a
> > > useful general feature.
> >
> > If you copy your U-Boot to RAM, you can have multiple U-Boots
> > each linked to the same location.
> > You need a small utility which runs before U-Boot which
> > determines which version to use.
>
> Hm... yes.  Though I think that is more of a workaround than a truly
> relocatable u-boot.

Yes, the relocation in U-Boot still is a big problem. There was a series of 
mails some time ago that at least described how it could be done correctly. 
Unfortunately no real acceptable patch till now.

IIRC, Grant Likely had some relocation fixes in his patch queue too. But he is 
most likely busy with other high priority stuff too (as we all are, 
right? ;)).

Best regards,
Stefan

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[U-Boot-Users] Relocatable U-Boot

[Ulf Samuelsson]

>> > > A handful of projects I have worked on use multiple copies of u-boot
>> > > stored in different locations of flash and a small assembly stub
>> > > determines which to boot.  Currently, to do that u-boot has to be
>> > > compiled two different times with different settings to accommodate
>> > > the different base addresses.
>> > >
>> > > Is there a way to use a single build of u-boot which can be placed at
>> > > two different addresses in flash?  That seems to me that it would be a
>> > > useful general feature.
>> >
>> > If you copy your U-Boot to RAM, you can have multiple U-Boots
>> > each linked to the same location.
>> > You need a small utility which runs before U-Boot which
>> > determines which version to use.
>>
>> Hm... yes.  Though I think that is more of a workaround than a truly
>> relocatable u-boot.
> 

I don't think having relocatable U-Boot is a good goal.
Having the possiblility to choose between several different U-boot image is...
Copying the image to SDRAM is one method to do this.
If you don't want to copy to SDRAM, then you can 
enable a MMU (when this is available) as an alternative.


Best Regards
Ulf Samuelsson

[U-Boot-Users] Relocatable U-Boot

[Ulf Samuelsson]

>> > > A handful of projects I have worked on use multiple copies of u-boot
>> > > stored in different locations of flash and a small assembly stub
>> > > determines which to boot.  Currently, to do that u-boot has to be
>> > > compiled two different times with different settings to accommodate
>> > > the different base addresses.
>> > >
>> > > Is there a way to use a single build of u-boot which can be placed at
>> > > two different addresses in flash?  That seems to me that it would be a
>> > > useful general feature.
>> >
>> > If you copy your U-Boot to RAM, you can have multiple U-Boots
>> > each linked to the same location.
>> > You need a small utility which runs before U-Boot which
>> > determines which version to use.
>>
>> Hm... yes.  Though I think that is more of a workaround than a truly
>> relocatable u-boot.
> 

I don't think having relocatable U-Boot is a good goal.
Having the possiblility to choose between several different U-boot image is...
Copying the image to SDRAM is one method to do this.
If you don't want to copy to SDRAM, then you can 
enable a MMU (when this is available) as an alternative.


Best Regards
Ulf Samuelsson