[U-Boot] reloacting uboot

[U-Boot] reloacting uboot

[E Robertson]

Hi All,
I am using the at91sam9263 device from which the bootstrap code load u-boot to 
the desired ram address. However, I would like to re-relocate this at the 
different address based on memory availability. Can / or should this be done? 

[U-Boot] reloacting uboot

[Wolfgang Denk]

Dear E Robertson,

In message <200908251403.20809.e.robertson.svg@gmail.com> you wrote:
>
> I am using the at91sam9263 device from which the bootstrap code load u-boot to 
> the desired ram address. However, I would like to re-relocate this at the 
> different address based on memory availability. Can / or should this be done? 

Yes, it can be done, and it should be done. The fact that we don't do
it so far is due to the fact that the guys who did the original ARM
code found this too complicated (even though they had a working
example in the PowerPC code) and not worth the effort. We're suffering
since from this misconception.

But there is no reason why you would have to copy the  code  again  -
just copy it to the correct address right from the beginning, like we
do in PowerPC.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
f u cn rd ths, itn tyg h myxbl cd.

[U-Boot] reloacting uboot

[E Robertson]

On Tuesday 25 August 2009 02:11:36 pm Wolfgang Denk wrote:
> Dear E Robertson,
>
> In message <200908251403.20809.e.robertson.svg@gmail.com> you wrote:
> > I am using the at91sam9263 device from which the bootstrap code load
> > u-boot to the desired ram address. However, I would like to re-relocate
> > this at the different address based on memory availability. Can / or
> > should this be done?
>
> Yes, it can be done, and it should be done. The fact that we don't do
> it so far is due to the fact that the guys who did the original ARM
> code found this too complicated (even though they had a working
> example in the PowerPC code) and not worth the effort. We're suffering
> since from this misconception.
>
> But there is no reason why you would have to copy the  code  again  -
> just copy it to the correct address right from the beginning, like we
> do in PowerPC.

I don't follow: Yes, but no reason to do so?
On the 9263, it's copied once to ram at boot. Are you saying their is no 
reason to copy it again? If so, yes, in most cases that would be true but I 
would like to move it again after that initial relocation. Since I've already 
specified my start address, I wasn't sure about.

[U-Boot] reloacting uboot

[E Robertson]

On Tuesday 25 August 2009 02:11:36 pm Wolfgang Denk wrote:
> Dear E Robertson,
>
> In message <200908251403.20809.e.robertson.svg@gmail.com> you wrote:
> > I am using the at91sam9263 device from which the bootstrap code load
> > u-boot to the desired ram address. However, I would like to re-relocate
> > this at the different address based on memory availability. Can / or
> > should this be done?
>
> Yes, it can be done, and it should be done. The fact that we don't do
> it so far is due to the fact that the guys who did the original ARM
> code found this too complicated (even though they had a working
> example in the PowerPC code) and not worth the effort. We're suffering
> since from this misconception.
>
> But there is no reason why you would have to copy the  code  again  -
> just copy it to the correct address right from the beginning, like we
> do in PowerPC.

By the way, my reason for doing this is that i want to maintain a proportional 
memory space available so if I increase the ram size I would like to relocate 
the boot loader without doing a separate build. Make sense?

[U-Boot] reloacting uboot

[Wolfgang Denk]

Dear E Robertson,

In message <200908251428.55255.e.robertson.svg@gmail.com> you wrote:
>
> > In message <200908251403.20809.e.robertson.svg@gmail.com> you wrote:
> > > I am using the at91sam9263 device from which the bootstrap code load
> > > u-boot to the desired ram address. However, I would like to re-relocate
> > > this at the different address based on memory availability. Can / or
> > > should this be done?
> >
> > Yes, it can be done, and it should be done. The fact that we don't do
> > it so far is due to the fact that the guys who did the original ARM
> > code found this too complicated (even though they had a working
> > example in the PowerPC code) and not worth the effort. We're suffering
> > since from this misconception.
> >
> > But there is no reason why you would have to copy the  code  again  -
> > just copy it to the correct address right from the beginning, like we
> > do in PowerPC.
> 
> I don't follow: Yes, but no reason to do so?

You wrote: "re-relocate". This is bogus. Just relocate it once, to the
correct address.

> On the 9263, it's copied once to ram at boot. Are you saying their is no 
> reason to copy it again? If so, yes, in most cases that would be true but I 
> would like to move it again after that initial relocation. Since I've already 
> specified my start address, I wasn't sure about.

Fix the ARM relocating scheme such that it works like in PowerPC: link
the image not for a RAM address, but for the address in flash. Then,
after determining the RAM size, copy & relocate the code once to RAM.
Only one copy. Not two.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Old programmers never die, they just branch to a new address.

[U-Boot] reloacting uboot

[Wolfgang Denk]

Dear E Robertson,

In message <200908251442.53461.e.robertson.svg@gmail.com> you wrote:
>
> By the way, my reason for doing this is that i want to maintain a proportional 
> memory space available so if I increase the ram size I would like to relocate 
> the boot loader without doing a separate build. Make sense?

That's how it's supposed to be. On PowerPC, we will relocate U-Boot to
the very end of available RAM. 

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
It's certainly  convenient  the  way  the  crime  (or  condition)  of
stupidity   carries   with   it  its  own  punishment,  automatically
admisistered without remorse, pity, or prejudice. :-)
         -- Tom Christiansen in <559seq$ag1$1@csnews.cs.colorado.edu>

[U-Boot] reloacting uboot

[Ulf Samuelsson]

Wolfgang Denk skrev:
> Dear E Robertson,
> 
> In message <200908251428.55255.e.robertson.svg@gmail.com> you wrote:
>>> In message <200908251403.20809.e.robertson.svg@gmail.com> you wrote:
>>>> I am using the at91sam9263 device from which the bootstrap code load
>>>> u-boot to the desired ram address. However, I would like to re-relocate
>>>> this at the different address based on memory availability. Can / or
>>>> should this be done?
>>> Yes, it can be done, and it should be done. The fact that we don't do
>>> it so far is due to the fact that the guys who did the original ARM
>>> code found this too complicated (even though they had a working
>>> example in the PowerPC code) and not worth the effort. We're suffering
>>> since from this misconception.
>>>
>>> But there is no reason why you would have to copy the  code  again  -
>>> just copy it to the correct address right from the beginning, like we
>>> do in PowerPC.
>> I don't follow: Yes, but no reason to do so?
> 
> You wrote: "re-relocate". This is bogus. Just relocate it once, to the
> correct address.
> 
>> On the 9263, it's copied once to ram at boot. Are you saying their is no 
>> reason to copy it again? If so, yes, in most cases that would be true but I 
>> would like to move it again after that initial relocation. Since I've already 
>> specified my start address, I wasn't sure about.
> 
> Fix the ARM relocating scheme such that it works like in PowerPC: link
> the image not for a RAM address, but for the address in flash. Then,
> after determining the RAM size, copy & relocate the code once to RAM.
> Only one copy. Not two.
> 
> Best regards,
> 
> Wolfgang Denk
> 

Very few boards based on the SAM9263 store u-boot in parallel flash
and if they are stored in SPI dataflash or in NAND flash it makes
little sense to link the u-boot to the flash address.

Fix at91bootstrap to load where you want it to load.

BR
Ulf Samuelsson