Newbie question

Newbie question

[Masahiro Yamada]

Hi.


Please forgive me if I am asking a silly newbie question.

I have some knowledge of U-Boot
but I have just started digging into barebox.


My simple question is, something like SPL
(secondary program loader) in U-boot is covered by barebox?



I assume the following steps
for running Linux on our boards by booting from NAND device.


[1] BootROM (hard-wired)

[2] Tiny boot program
    for initializing SDRAM, etc.

[3] High-level boot loader
    for loading the kernel, handling device tree etc.

[4] Linux



I guess [3] is covered by barebox.

Is [2] supported by barebox? Or is it like Do-It-Yourself thing?


Best Regards
Masahiro Yamada


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Re: Newbie question

[Sascha Hauer]

Hi,

On Wed, Oct 01, 2014 at 07:35:34PM +0900, Masahiro Yamada wrote:
> Hi.
> 
> 
> Please forgive me if I am asking a silly newbie question.
> 
> I have some knowledge of U-Boot
> but I have just started digging into barebox.
> 
> 
> My simple question is, something like SPL
> (secondary program loader) in U-boot is covered by barebox?

Yes, it is, in barebox it's called PBL (PreBootLoader).

If enabled the ROM will load the PBL from the boot device (Or sometimes
the whole image, depends on the ROM). The PBL will then load the rest
of the image from the device, uncompress it and jump to it.

> [1] BootROM (hard-wired)
> 
> [2] Tiny boot program
>     for initializing SDRAM, etc.
> 
> [3] High-level boot loader
>     for loading the kernel, handling device tree etc.
> 
> [4] Linux
> 
> 
> 
> I guess [3] is covered by barebox.
> 
> Is [2] supported by barebox? Or is it like Do-It-Yourself thing?

Well, there's infrastructure for it, but due to the limited space
and restricted environment in the PBL there's still some DIY left ;)

Sascha

-- 
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Re: Newbie question

[Masahiro Yamada]

Hi Sascha,



On Wed, 1 Oct 2014 14:06:43 +0200
Sascha Hauer <s.hauer@pengutronix.de> wrote:

> Hi,
> 
> On Wed, Oct 01, 2014 at 07:35:34PM +0900, Masahiro Yamada wrote:
> > Hi.
> > 
> > 
> > Please forgive me if I am asking a silly newbie question.
> > 
> > I have some knowledge of U-Boot
> > but I have just started digging into barebox.
> > 
> > 
> > My simple question is, something like SPL
> > (secondary program loader) in U-boot is covered by barebox?
> 
> Yes, it is, in barebox it's called PBL (PreBootLoader).
> 
> If enabled the ROM will load the PBL from the boot device (Or sometimes
> the whole image, depends on the ROM). The PBL will then load the rest
> of the image from the device, uncompress it and jump to it.
> 
> > [1] BootROM (hard-wired)
> > 
> > [2] Tiny boot program
> >     for initializing SDRAM, etc.
> > 
> > [3] High-level boot loader
> >     for loading the kernel, handling device tree etc.
> > 
> > [4] Linux
> > 
> > 
> > 
> > I guess [3] is covered by barebox.
> > 
> > Is [2] supported by barebox? Or is it like Do-It-Yourself thing?
> 
> Well, there's infrastructure for it, but due to the limited space
> and restricted environment in the PBL there's still some DIY left ;)
> 



Now I understood how it works.

 obj-y  => Main barebox
 pbl-y  => PBL


Thanks!



Best Regards
Masahiro Yamada


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