Question about uboot initialisation

[Simon Glass]

Hi Aubin,

On Mon, 12 Sept 2022 at 09:13, momo aubin <aubinno at gmail.com> wrote:
>
>
>
> On Mon, 12 Sept 2022 at 17:07, Simon Glass <sjg at chromium.org> wrote:
>>
>> Hi Aubin,
>>
>> On Mon, 12 Sept 2022 at 08:23, momo aubin <aubinno at gmail.com> wrote:
>> >
>> > Hi Simon,
>> >
>> > Thanks for your answer and explanations.
>> >
>> > The sequence of boot is :
>> > RBL->UBL->UBOOT->Kernel->ROOTFS.
>> >
>> > According to this sequence, ubl is the one who chooses which uboot needs to be started, then writing the script means writing them inside ubl. However, Ubl doesn't have access to the environment variable  in order to know which u-boot has been used first.
>> >
>> > My question is .
>> > Is it possible to choose another u-boot (u-boot2) inside the first u-boot (u-boot1) ?
>>
>> Can you please try that reply again, without top posting?
>>
>> https://www.google.com/search?q=top+posting
>>
>> Regards,
>> Simon
>>
>>
>> >
>> > Regards,
>> > Aubin
>> >
>> > On Mon, 12 Sept 2022 at 15:35, Simon Glass <sjg at chromium.org> wrote:
>> >>
>> >> Hi Momo,
>> >>
>> >> On Sun, 11 Sept 2022 at 08:29, momo aubin <aubinno at gmail.com> wrote:
>> >> >
>> >> > Hi Simon,
>> >> >
>> >> > Thanks for getting back to me.
>> >> >
>> >> > How can I avoid top posting ? i'm a new
>> >>
>> >> You can do a web search for "top posting" which explains the issue
>> >> better than I can.
>> >>
>> >> >
>> >> > How uboot know that the kernel has started ?
>> >>
>> >> Generally it does not. U-Boot's job is typically over once it jumps to
>> >> the kernel.
>> >>
>> >> > If the system is blocked during the u-boot stage, is it possible to restart all the systems ?
>> >> > It is possible to put a timer in the u-boot stage in case of the kernel has not started , can the system reboot by choosing another u-boot ?
>> >>
>> >> You can use a watchdog timer to reboot the system. It can be set up in
>> >> U-Boot, then it Linux does not kick it in time, it will cause a
>> >> reboot. To choose another U-Boot, you would need to do some scripting,
>> >> or use mender. There is some work on VBE going on (U-Boot standard
>> >> boot) but it will take a while to all land.
>> >>
>> >> Regards,
>> >> SImon
>> >>
>> >>
>> >> >
>> >> >
>> >> > Thanks for your answer in advance.
>> >> > Aubin
>> >> >
>> >> >
>> >> > On Tue, 30 Aug 2022 at 04:30, Simon Glass <sjg at chromium.org> wrote:
>> >> >>
>> >> >> Hi Aubin,
>> >> >>
>> >> >> On Mon, 29 Aug 2022 at 01:40, momo aubin <aubinno at gmail.com> wrote:
>> >> >> >
>> >> >> > Hi Simon,
>> >> >> > I got what is the 'dm tree' which is a driver model. This command could be done only in uboot stage. but i got the situation in which the initialisation of u-boot has not finished yet as showing in the following picture.
>> >> >> >
>> >> >> >
>> >> >> >  .i would like to know what is wrong in the initialisation ?
>> >> >>
>> >> >> Please try to avoid top posting.
>> >> >>
>> >> >> I think the best thing is to move to the latest U-Boot. You are about
>> >> >> 9 years behind! But as to your question, I am really not sure. If it
>> >> >> is a TI board, you could try asking them?
>> >> >>
>> >> >> Regards,
>> >> >> Simon
>> >> >>
>> >> >>
>> >> >> >
>> >> >> > Best Regard,
>> >> >> > Aubin
>> >> >> >
>> >> >> > On Mon, 29 Aug 2022 at 05:24, momo aubin <aubinno at gmail.com> wrote:
>> >> >> >>
>> >> >> >> Hi Simon,
>> >> >> >>
>> >> >> >> Thanks for your answer.
>> >> >> >>
>> >> >> >> The script that you are telling it is Env.txt right ?
>> >> >> >>
>> >> >> >> What is a 'dm tree' ? Please could you provide me more infos about this ?
>> >> >> >>
>> >> >> >> Thanks for your answer in advance.
>> >> >> >>
>> >> >> >> On Sat, 27 Aug 2022 at 02:21, Simon Glass <sjg at chromium.org> wrote:
>> >> >> >>>
>> >> >> >>> Hi Aubin,
>> >> >> >>>
>> >> >> >>> On Fri, 26 Aug 2022 at 06:41, momo aubin <aubinno at gmail.com> wrote:
>> >> >> >>> >
>> >> >> >>> > Dear all,
>> >> >> >>> >
>> >> >> >>> >
>> >> >> >>> > Is there any way that allows us to know that uboot has initialised all his
>> >> >> >>> > peripherals before starting loading kernel ?
>> >> >> >>> >
>> >> >> >>> > The goal of this check is to reset the board in case of bad initialisation
>> >> >> >>> > and choose a different uboot .
>> >> >> >>> >
>> >> >> >>> > Thanks for your answer in advance.
>> >> >> >>> > Aubin
>> >> >> >>>
>> >> >> >>> If there is a failure then it likely results in an error-return code
>> >> >> >>> from board_init_f() or board_init_r(). These generally halt U-Boot /
>> >> >> >>> cause a reboot. But this only covers the peripherals that U-Boot sets
>> >> >> >>> up early, like serial, clocks, pinctrl, MMC, PCI, etc.
>> >> >> >>>
>> >> >> >>> U-Boot typically does not init a peripheral unless it is needed for U-Boot.
>> >> >> >>>
>> >> >> >>> While U-Boot is running (e.g. a script) it may start up other
>> >> >> >>> peripherals (e.g. to read a kernel from USB) and in those cases errors
>> >> >> >>> can be handled by the script.
>> >> >> >>>
>> >> >> >>> You can use 'dm tree' to see what devices have been probed successfully.
>> >> >> >>>
>> >> >> >>> Regards,
>> >> >> >>> Simon
>
>
> Hi Simon,
>
> Thanks for your answer and explanations.
>
> The sequence of boot is :
> RBL->UBL->UBOOT->Kernel->ROOTFS.
>
> According to this sequence, ubl is the one who chooses which uboot needs to be started, then writing the script means writing them inside ubl. However, Ubl doesn't have access to the environment variable  in order to know which u-boot has been used first.

I don't know what RBL and UBL are.

>
> My question is .
> Is it possible to choose another u-boot (u-boot2) inside the first u-boot (u-boot1) ?

Yes you can jump from one U-Boot to another. Something like 'dcache
off; go <addr>' should work.


>
> Is this correct ?

Regards,
Simon