[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Shawn Jin]

Hi,

Can an old u-boot (e.g. 1.1.2) boot a latest powerpc based kernel
(e.g. 2.6.33)? I noticed that the bd_info in the latest u-boot is
different from the one in 1.1.2. The custom board with u-boot 1.1.2
passed only the first 6 parameters to a 2.4 kernel shown as below.

typedef struct bd_info {
/*======================================================================*/
	unsigned long	bi_memstart;	/* start of DRAM memory */
	unsigned long	bi_memsize;	/* size	 of DRAM memory in bytes */
	unsigned long	bi_intfreq;		/* Internal Freq, in MHz */
	unsigned long	bi_busfreq;		/* Bus Freq, in MHz */
	unsigned char	bi_enetaddr[6];	/* Ethernet adress */
	unsigned long	bi_baudrate;	/* Console Baudrate */
	unsigned long	bi_flashstart;	/* start of FLASH memory */
	unsigned long	bi_flashsize;	/* size	 of FLASH memory */
	unsigned long	bi_flashoffset; /* reserved area for startup monitor */
	unsigned long	bi_sramstart;	/* start of SRAM memory */
	unsigned long	bi_sramsize;	/* size	 of SRAM memory */
#if defined(CONFIG_5xx) || defined(CONFIG_8xx) || defined(CONFIG_8260) \
	|| defined(CONFIG_E500)
	unsigned long	bi_immr_base;	/* base of IMMR register */
#endif
<...snipped>
}

The customer does't want to upgrade u-boot. If linux drivers are
ported to the new powerpc arch, is u-boot 1.1.2 still able to boot the
new kernel? Besides the bd_info, what else the powerpc kernel expect
from u-boot?

Thanks,
-Shawn.

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Timur Tabi]

On Thu, May 13, 2010 at 1:43 AM, Shawn Jin <shawnxjin@gmail.com> wrote:

> The customer does't want to upgrade u-boot. If linux drivers are
> ported to the new powerpc arch, is u-boot 1.1.2 still able to boot the
> new kernel? Besides the bd_info, what else the powerpc kernel expect
> from u-boot?

The only way to find out for sure is to test it.  You'll probably need
to enable cuImage support in the kernel, at the very least.  No one
keeps track of whether newer kernels work with older U-Boots, so
there's no way to know in advance whether a specific kernel and a
specific device tree and a specific (older) U-Boot will work together.

-- 
Timur Tabi
Linux kernel developer at Freescale

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Shawn Jin]

On Thu, May 13, 2010 at 7:47 AM, Timur Tabi <timur@freescale.com> wrote:
> The only way to find out for sure is to test it. ?You'll probably need
> to enable cuImage support in the kernel, at the very least. ?No one
> keeps track of whether newer kernels work with older U-Boots, so
> there's no way to know in advance whether a specific kernel and a
> specific device tree and a specific (older) U-Boot will work together.

Thanks for the comments.

However my concern is specific to the powerpc arch. If I understand
correctly, the powerpc arch expects a bootloader provide a DTS file.
I'm not sure how the current U-Boot transfers such info to the
kernerl. People here can shed some light on this? I'm certain the old
U-Boot (e.g. 1.1.2) doesn't have this kind of capability. The bd_info
is still one of data transferred to the kernel, right? How does
bd_info work with the DTS info?

Thanks,
-Shawn.

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Wolfgang Denk]

Dear Shawn Jin,

In message <AANLkTik4dbCkniKRuJ4JtMpHpQiLDgbXtw5Ihby0XFOx@mail.gmail.com> you wrote:
> On Thu, May 13, 2010 at 7:47 AM, Timur Tabi <timur@freescale.com> wrote:
> > The only way to find out for sure is to test it.  You'll probably need
> > to enable cuImage support in the kernel, at the very least.  No one
-------^^^^^^^^^^^^^^

> However my concern is specific to the powerpc arch. If I understand
> correctly, the powerpc arch expects a bootloader provide a DTS file.

Not if you use a cuImage as Timur suggested.

> I'm not sure how the current U-Boot transfers such info to the
> kernerl. People here can shed some light on this? I'm certain the old
> U-Boot (e.g. 1.1.2) doesn't have this kind of capability. The bd_info

It would be easier if you upgraded to a recent version of U-Boot of
course.

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
"I'm not a god, I was misquoted."                 - Lister, Red Dwarf

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Timur Tabi]

Shawn Jin wrote:

> However my concern is specific to the powerpc arch. If I understand
> correctly, the powerpc arch expects a bootloader provide a DTS file.
> I'm not sure how the current U-Boot transfers such info to the
> kernerl. 

One of the registers (r7 maybe?) contains the address of the device tree.

> People here can shed some light on this? I'm certain the old
> U-Boot (e.g. 1.1.2) doesn't have this kind of capability.

That's why cuImage was invented.  cuImage embeds the device tree in the
kernel image.  The drawback is that you can't rely on U-Boot to do any fixups.

> The bd_info
> is still one of data transferred to the kernel, right? How does
> bd_info work with the DTS info?

That, I don't know.

-- 
Timur Tabi
Linux kernel developer at Freescale

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Shawn Jin]

>> However my concern is specific to the powerpc arch. If I understand
>> correctly, the powerpc arch expects a bootloader provide a DTS file.
>
> Not if you use a cuImage as Timur suggested.

Wolfgan & Timur, thanks for the comments.

-Shawn.

[U-Boot] u-boot 1.1.2 boot latest powerpc based kernel?

[Scott Wood]

On Mon, May 17, 2010 at 09:06:49AM -0500, Timur Tabi wrote:
> Shawn Jin wrote:
> 
> > However my concern is specific to the powerpc arch. If I understand
> > correctly, the powerpc arch expects a bootloader provide a DTS file.
> > I'm not sure how the current U-Boot transfers such info to the
> > kernerl. 
> 
> One of the registers (r7 maybe?) contains the address of the device tree.

r3

> > People here can shed some light on this? I'm certain the old
> > U-Boot (e.g. 1.1.2) doesn't have this kind of capability.
> 
> That's why cuImage was invented.  cuImage embeds the device tree in the
> kernel image.  The drawback is that you can't rely on U-Boot to do any fixups.

U-Boot itself can't do any fixups (because it doesn't know about the device
tree), but the cuImage bootwrapper does do some fixups (mainly memory size,
clock speed, and MAC address) based on the bd_info that U-Boot passes in. 
The drawback is that the bd_info is fragile and the information it passes is
limited.

> > The bd_info
> > is still one of data transferred to the kernel, right? 

Not in the new booting scheme.  cuImage will accept a bd_info instead of a
device tree (and will have a device tree built into the kernel).

-Scott