[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Ishwar Saunshi]

Hi All,

I am really curiuos to see if U-boot can boot another version or another
Uboot burnt in flash ?
Its like having 2 images of U-boot which can boot each other if it is
possible can any one of you hint me how I can achive this. I tried to
relocate the Uboot and burned on to the flash in 2 different loacation
however when I try to do "go <U-boot effective address>" it ends up in TLB
error in early stage of flash execution.


Thanks for the Help.
Ish

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Wolfgang Denk]

Dear Ishwar Saunshi,

In message <CAKD3hySShg8+XNX1yQNVDDLYQupgaJC-Lmg1qZ32cy5eBm6GQw@mail.gmail.com> you wrote:
> 
> I am really curiuos to see if U-boot can boot another version or another
> Uboot burnt in flash ?
> Its like having 2 images of U-boot which can boot each other if it is
> possible can any one of you hint me how I can achive this. I tried to
> relocate the Uboot and burned on to the flash in 2 different loacation
> however when I try to do "go <U-boot effective address>" it ends up in TLB
> error in early stage of flash execution.

In general, this is not possible.  This topic is covered in the FAQ
here:
http://www.denx.de/wiki/view/DULG/CanUBootBeConfiguredSuchThatItCanBeStartedInRAM


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
"Out of register space (ugh)"
- vi

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Ishwar Saunshi]

Thanks Wolfgang,

I have gone through the FAQ section, this FAQ only talks about the
condition where the other Uboot is in RAM but what I am thinking is to boot
the Uboot from the flash location by another running Uboot.

for example if my board flash starts from 0xC000_0000 to 0xCFFF_FFFF and
the first Uboot-1 is programmed @ 0xC800_0000 and second Uboot-2 is
programmed @0xC500_0000 on reset Uboot-1 starts from flash and load it self
to RAM and boots up and from there is it possible to boot Uboot-2 by using *
go* cmd or in any other way.


Regards,
ISHWAR


On Wed, Jun 27, 2012 at 7:19 PM, Wolfgang Denk <wd@denx.de> wrote:

> Dear Ishwar Saunshi,
>
> In message <
> CAKD3hySShg8+XNX1yQNVDDLYQupgaJC-Lmg1qZ32cy5eBm6GQw at mail.gmail.com> you
> wrote:
> >
> > I am really curiuos to see if U-boot can boot another version or another
> > Uboot burnt in flash ?
> > Its like having 2 images of U-boot which can boot each other if it is
> > possible can any one of you hint me how I can achive this. I tried to
> > relocate the Uboot and burned on to the flash in 2 different loacation
> > however when I try to do "go <U-boot effective address>" it ends up in
> TLB
> > error in early stage of flash execution.
>
> In general, this is not possible.  This topic is covered in the FAQ
> here:
>
> http://www.denx.de/wiki/view/DULG/CanUBootBeConfiguredSuchThatItCanBeStartedInRAM
>
>
> 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
> "Out of register space (ugh)"
> - vi
>

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Wolfgang Denk]

Dear Ishwar Saunshi,

please don't top post / full quote.

In message <CAKD3hyQuVMiBHY55mzbMttY7DYEhu8o3p+AWY+GFr0ndhdn8Cw@mail.gmail.com> you wrote:
> 
> I have gone through the FAQ section, this FAQ only talks about the
> condition where the other Uboot is in RAM but what I am thinking is to boot
> the Uboot from the flash location by another running Uboot.

This doesn't make any difference.  Read more carefully, and read to
the end.  Pay special attention to the part here:

	U-Boot expects to see a virgin CPU, i. e. the CPU state must
	match what you see if the processor starts executing the first
	instructions when it comes out of reset. If you want to start
	U-Boot from another boot loader, you must disable a lot of
	code ...



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
You don't have to stay up nights to succeed; you have to  stay  awake
days.

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Schneider, Kolja]

Dear Ishwar Saunshi,
> >
> > I have gone through the FAQ section, this FAQ only talks about the
> > condition where the other Uboot is in RAM but what I am thinking is to
> boot
> > the Uboot from the flash location by another running Uboot.
> 
> This doesn't make any difference.  Read more carefully, and read to
> the end.  Pay special attention to the part here:
> 
> 	U-Boot expects to see a virgin CPU, i. e. the CPU state must
> 	match what you see if the processor starts executing the first
> 	instructions when it comes out of reset. If you want to start
> 	U-Boot from another boot loader, you must disable a lot of
> 	code ...
> 

This is really highly CPU-dependent. We are using something like that to 
implement a fallback u-boot image in case someone manages to kill
the standard image, it was quite easy to do for e.g. mpc512x, but quite some 
coding effort for mpc85XX. The corresponding code always looks 
slightly insane. If you feel like diving in deep into the innards of
your CPU, go for it. If you don't really need it, skip it.

:-) Kolja

> 
> 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
> You don't have to stay up nights to succeed; you have to  stay  awake
> days.
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Ishwar Saunshi]

Thanks Wolfgang & Kolja,

Kolja,

I wanted to do the same with the other Uboot what you have
already achieved, Infact I am using mpc85xx too. could you please list out
the changes you made.


Thanks for the help.