[U-Boot] uboot redundancy.

[Sagar Heroorkar]

resending this.

Please do reply

-Sagar

On Fri, Jul 16, 2010 at 3:12 PM, Sagar Heroorkar
<sagar.heroorkar at gmail.com>wrote:

> Hi Joakim,
>
> Graeme referred me to contact you for this.
>
> I am working on U-boot making it PIC for ppc 405ex based boards.
> I see in the following link
> http://www.mail-archive.com/u-boot@lists.denx.de/msg26918.html
> that you have implemented similar thing on 83xx board.
>
> I have downloaded latest u-boot from ftp server of denx. I dont see the
> functions what you have modified like LINKF_OFF() etc.
>  I would like to know where is the source code for that. Also is there any
> document other than the mail thread that explains what you have chagned.
>
> Thanks in advance.
>
> -Sagar
>
>
> On Sat, Jul 10, 2010 at 7:11 AM, Graeme Russ <graeme.russ at gmail.com>wrote:
>
>> On 10/07/10 00:03, Sagar Heroorkar wrote:
>> > Hi All,
>> >
>> > I am planning to implement uboot redundancy.
>> > This means having the following idea which we thought.
>> >
>> > Golden-Uboot which is flashed in the NOR-FLASH. This is not field
>> > upgradable.
>> > This golden uboot is going to have logic to pick the other uboot based
>> on
>> > certain flags or env vriables
>> >
>> > As i mentioned i wanted the uboot to be redundant.
>> > So i will have 2 copies of uboot now.
>> > Uboot1
>> > Uboot2
>>
>> I have a similar plan for x86 although the rationale was to enable rapid
>> load-reset-test(-write to boot ROM on pass).
>>
>> The x86 port has the ability to load a new version of U-Boot into an
>> arbitrary location in RAM and 'boot-strap' directly into it. I was
>> planning
>> on doing something similar to what you propose - All that is needed is a
>> little bit of code in the low-level boot-strap to choose whether to
>> continue loading the main image, or a secondary image. Note that at this
>> point, there is no environment and no CFI driver so any decision would
>> need
>> to be based on NVRAM data.
>>
>> >
>> > Golden uboot will pick either of one uboots mentioned above. If the
>> uboot1
>> > which is picked fails to boot, then we will have uboot2 as back up to
>> boot.
>> > vice versa.
>> >
>> > Golden uboot recides in the address fffa0000 (start.s).
>> > There is a relocation code which copies the code from flash to ram. if
>> the
>> > uboot which i have picked addressess will change , hence how can i do
>> the
>> > relocation?
>>
>> x86 port has 'proper' relocation. It does not matter where the target
>> image
>> resides, it will reload itself into the highest available memory location
>> and run from there.
>>
>> >
>> > Any pointers will help me if any one already did this kind of approach
>> > making uboot redundant.
>> >
>>
>> There were some posts a little while ago (search for posts by Joakim
>> Tjernlund - he was working on a 100% position independent U-Boot)
>>
>> My work on U-Boot has been very slow of late, but I would be really
>> interested in working through this idea in a platform independent way.
>>
>> --
>> Graeme
>>
>
>