[U-Boot] Can u-Boot Ran from RAM?

[U-Boot] Can u-Boot Ran from RAM?

[Bud Miljkovic]

Hi there,

 

While getting acquainted with possible u-Boot development issues, I read
FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
RAM?" and was puzzled to learn that u-Boot cannot run from RAM.

 

Considering a custom platform, using i.MX536, I understand that the
i.MX53x processor has its own ROM-based code that performs boot time
essential devices initialisation, etc.  In the case when NAND flash is
the program-image medium at the boot stage, first, the ROM-based code
checks for Discovered Bad Blocks Table (DBBT) presence and searches for
valid Firmware Configuration Block (FCB) on external NAND Flash.  

 

If FCB is found that points to the NAND Flash page(s) that contain the
first 4K of initial firmware to be loaded from NAND Flash. Then, it
loads the 4K of data, pointed by FCB, into the NFC RAM buffer. These
data contain a valid Image Vector Table (IVT).  Then, the ROM-based code
processes IVT, executes the Device Configuration Data (DCD) sequences to
initialize boot-related integrated peripherals (typically, these are
IOMUX, SDRAM controller and boot memory controller), then copies the
application code, also contained in IVT, to target memory (typically,
SDRAM) and jumps to it. Typically, this application code is the custom
primary bootloader that completes loading the application code (e.g.
main OS bootloader) and passes the control to it.

 

If FCB is not found the ROM-based code starts executing a download
protocol over UART or USB port in an attempt to get a valid IVT from a
host.  If the IVT is eventually obtained it is processed as before.

 

So the question is can this "custom primary bootloader" role, in fact,
be played by u-Boot.  Reading your text of FAQ 14.2.1., it seems to me
that it cannot.  On the other hand I know of some Freescale i.MX53x demo
boards (e.g. ARD, LOCO) that use u-Boot. 

 

I wonder what I'm missing here.

 

Regards,

Bud

 

[U-Boot] Can u-Boot Ran from RAM?

[Eric Nelson]

On 01/30/2012 09:07 PM, Bud Miljkovic wrote:
> Hi there,
>
>
>
> While getting acquainted with possible u-Boot development issues, I read
> FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> RAM?" and was puzzled to learn that u-Boot cannot run from RAM.
>
>
>
> Considering a custom platform, using i.MX536, I understand that the
> i.MX53x processor has its own ROM-based code that performs boot time
> essential devices initialisation, etc.  In the case when NAND flash is
> the program-image medium at the boot stage, first, the ROM-based code
> checks for Discovered Bad Blocks Table (DBBT) presence and searches for
> valid Firmware Configuration Block (FCB) on external NAND Flash.
>
>
>
> If FCB is found that points to the NAND Flash page(s) that contain the
> first 4K of initial firmware to be loaded from NAND Flash. Then, it
> loads the 4K of data, pointed by FCB, into the NFC RAM buffer. These
> data contain a valid Image Vector Table (IVT).  Then, the ROM-based code
> processes IVT, executes the Device Configuration Data (DCD) sequences to
> initialize boot-related integrated peripherals (typically, these are
> IOMUX, SDRAM controller and boot memory controller), then copies the
> application code, also contained in IVT, to target memory (typically,
> SDRAM) and jumps to it. Typically, this application code is the custom
> primary bootloader that completes loading the application code (e.g.
> main OS bootloader) and passes the control to it.
>
>
>
> If FCB is not found the ROM-based code starts executing a download
> protocol over UART or USB port in an attempt to get a valid IVT from a
> host.  If the IVT is eventually obtained it is processed as before.
>
>
>
> So the question is can this "custom primary bootloader" role, in fact,
> be played by u-Boot.  Reading your text of FAQ 14.2.1., it seems to me
> that it cannot.  On the other hand I know of some Freescale i.MX53x demo
> boards (e.g. ARD, LOCO) that use u-Boot.
>
>
>
> I wonder what I'm missing here.
>

I think that FAQ is a bit misleading and really refers to using another boot
loader to load U-Boot.

On all i.MX processors I've had the pleasure of using, U-Boot runs only
from RAM. I think you probably knew this because very few i.MX designs
even have other memory (i.e. NOR flash) that allows XIP.

For instance, the LOCO certainly isn't running __from__ SD card.

Take a look at the link maps for builds of these platforms to clarify.

[U-Boot] Can u-Boot Ran from RAM?

[Mike Frysinger]

On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> While getting acquainted with possible u-Boot development issues, I read
> FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> RAM?" and was puzzled to learn that u-Boot cannot run from RAM.

you misread it.  the question is for people who have loaded u-boot, and then 
want to load another copy of u-boot into ram and then execute that directly.

so the question is "can u-boot be *started in ram*" and the answer is "no".  
normally u-boot is bootstrapped from non-ram storage (via a bootrom, or some 
bit of code being latched in at a hardcoded address, or some other cpu-specific 
magic).
-mike
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[U-Boot] Can u-Boot Ran from RAM?

[Charles Manning]

On Tuesday 31 January 2012 17:07:05 Bud Miljkovic wrote:
> Hi there,
>
>
>
> While getting acquainted with possible u-Boot development issues, I read
> FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> RAM?" and was puzzled to learn that u-Boot cannot run from RAM.

This is clearly not true.

The omap devices and davinci devices both use rom boot loaders to load uboot 
into ram for further execution.

In the case of omaps it is often even more complex using a rom boot loader to 
load x-load (or cut down u-boot) to load the real uboot which then loads 
Linux.

-- Charles

[U-Boot] Can u-Boot Ran from RAM?

[Marek Vasut]

> On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > While getting acquainted with possible u-Boot development issues, I read
> > FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> > RAM?" and was puzzled to learn that u-Boot cannot run from RAM.
> 
> you misread it.  the question is for people who have loaded u-boot, and
> then want to load another copy of u-boot into ram and then execute that
> directly.
> 
> so the question is "can u-boot be *started in ram*" and the answer is "no".

The answer is "yes if you know how to do it" ;-)

> normally u-boot is bootstrapped from non-ram storage (via a bootrom, or
> some bit of code being latched in at a hardcoded address, or some other
> cpu-specific magic).
> -mike

[U-Boot] Can u-Boot Ran from RAM?

[Marek Vasut]

> On 01/30/2012 09:07 PM, Bud Miljkovic wrote:
> > Hi there,
> > 
> > 
> > 
> > While getting acquainted with possible u-Boot development issues, I read
> > FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> > RAM?" and was puzzled to learn that u-Boot cannot run from RAM.
> > 
> > 
> > 
> > Considering a custom platform, using i.MX536, I understand that the
> > i.MX53x processor has its own ROM-based code that performs boot time
> > essential devices initialisation, etc.  In the case when NAND flash is
> > the program-image medium at the boot stage, first, the ROM-based code
> > checks for Discovered Bad Blocks Table (DBBT) presence and searches for
> > valid Firmware Configuration Block (FCB) on external NAND Flash.
> > 
> > 
> > 
> > If FCB is found that points to the NAND Flash page(s) that contain the
> > first 4K of initial firmware to be loaded from NAND Flash. Then, it
> > loads the 4K of data, pointed by FCB, into the NFC RAM buffer. These
> > data contain a valid Image Vector Table (IVT).  Then, the ROM-based code
> > processes IVT, executes the Device Configuration Data (DCD) sequences to
> > initialize boot-related integrated peripherals (typically, these are
> > IOMUX, SDRAM controller and boot memory controller), then copies the
> > application code, also contained in IVT, to target memory (typically,
> > SDRAM) and jumps to it. Typically, this application code is the custom
> > primary bootloader that completes loading the application code (e.g.
> > main OS bootloader) and passes the control to it.
> > 
> > 
> > 
> > If FCB is not found the ROM-based code starts executing a download
> > protocol over UART or USB port in an attempt to get a valid IVT from a
> > host.  If the IVT is eventually obtained it is processed as before.
> > 
> > 
> > 
> > So the question is can this "custom primary bootloader" role, in fact,
> > be played by u-Boot.  Reading your text of FAQ 14.2.1., it seems to me
> > that it cannot.  On the other hand I know of some Freescale i.MX53x demo
> > boards (e.g. ARD, LOCO) that use u-Boot.
> > 
> > 
> > 
> > I wonder what I'm missing here.
> 
> I think that FAQ is a bit misleading and really refers to using another
> boot loader to load U-Boot.

The FAQ really means "is it possible to load u-boot from u-boot" ... which is 
possible in some cases, but officially unsupported.

> 
> On all i.MX processors I've had the pleasure of using, U-Boot runs only
> from RAM. I think you probably knew this because very few i.MX designs
> even have other memory (i.e. NOR flash) that allows XIP.
> 
> For instance, the LOCO certainly isn't running __from__ SD card.
> 
> Take a look at the link maps for builds of these platforms to clarify.

Yep, MX53 is well supported by mainline u-boot.

M

> 
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

[U-Boot] Can u-Boot Ran from RAM?

[Wolfgang Denk]

Dear Marek Vasut,

In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
> > On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > > While getting acquainted with possible u-Boot development issues, I read
> > > FAQ "14.2.1.  Can U-Boot be configured such that it can be started in
> > > RAM?" and was puzzled to learn that u-Boot cannot run from RAM.
> > 
> > you misread it.  the question is for people who have loaded u-boot, and
> > then want to load another copy of u-boot into ram and then execute that
> > directly.
> > 
> > so the question is "can u-boot be *started in ram*" and the answer is "no".
> 
> The answer is "yes if you know how to do it" ;-)

The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
and start it.  You must prepare a _special_ image which omits all the
initializations that are normally included.

This FAQ addresses the situation where people want to load and run
their _normal_ images before burning these to flash.  And this CANNOT
be done like that.

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
Reader, suppose you were an idiot. And suppose you were a  member  of
Congress. But I repeat myself.                           - Mark Twain

[U-Boot] Can u-Boot Ran from RAM?

[Wolfgang Denk]

Dear Marek Vasut,

In message <201202011112.28009.marek.vasut@gmail.com> you wrote:
>
> The FAQ really means "is it possible to load u-boot from u-boot" ... which is 
> possible in some cases, but officially unsupported.

This is your interpretation, and it is not quite correct.

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
To be sure of hitting the target, shoot first and, whatever you  hit,
call it the target.

[U-Boot] Can u-Boot Ran from RAM?

[Marek Vasut]

> Dear Marek Vasut,
> 
> In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
> > > On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > > > While getting acquainted with possible u-Boot development issues, I
> > > > read FAQ "14.2.1.  Can U-Boot be configured such that it can be
> > > > started in RAM?" and was puzzled to learn that u-Boot cannot run
> > > > from RAM.
> > > 
> > > you misread it.  the question is for people who have loaded u-boot, and
> > > then want to load another copy of u-boot into ram and then execute that
> > > directly.
> > > 
> > > so the question is "can u-boot be *started in ram*" and the answer is
> > > "no".
> > 
> > The answer is "yes if you know how to do it" ;-)
> 
> The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
> and start it.  You must prepare a _special_ image which omits all the
> initializations that are normally included.

You can on PXA ;-)
> 
> This FAQ addresses the situation where people want to load and run
> their _normal_ images before burning these to flash.  And this CANNOT
> be done like that.

You're certainly right this is true for general case, but there are special 
cases where you can load u-boot from u-boot without any harm (PXA is the 
example).

> 
> Best regards,
> 
> Wolfgang Denk

[U-Boot] Porting YAFFS2 to U-boot

[Bud Miljkovic]

I am newbie in this.  Anybody done it?  

Any lead is appreciated.

Cheers,
Bud Miljkovic

-----Original Message-----
From: Marek Vasut [mailto:marek.vasut at gmail.com] 
Sent: Wednesday, 1 February 2012 11:58 p.m.
To: Wolfgang Denk
Cc: u-boot at lists.denx.de; Bud Miljkovic
Subject: Re: [U-Boot] Can u-Boot Ran from RAM?

> Dear Marek Vasut,
> 
> In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
> > > On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > > > While getting acquainted with possible u-Boot development
issues, I
> > > > read FAQ "14.2.1.  Can U-Boot be configured such that it can be
> > > > started in RAM?" and was puzzled to learn that u-Boot cannot run
> > > > from RAM.
> > > 
> > > you misread it.  the question is for people who have loaded
u-boot, and
> > > then want to load another copy of u-boot into ram and then execute
that
> > > directly.
> > > 
> > > so the question is "can u-boot be *started in ram*" and the answer
is
> > > "no".
> > 
> > The answer is "yes if you know how to do it" ;-)
> 
> The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
> and start it.  You must prepare a _special_ image which omits all the
> initializations that are normally included.

You can on PXA ;-)
> 
> This FAQ addresses the situation where people want to load and run
> their _normal_ images before burning these to flash.  And this CANNOT
> be done like that.

You're certainly right this is true for general case, but there are
special 
cases where you can load u-boot from u-boot without any harm (PXA is the

example).

> 
> Best regards,
> 
> Wolfgang Denk

[U-Boot] Porting YAFFS2 to U-boot

[Mike Frysinger]

On Thursday 02 February 2012 16:40:45 Bud Miljkovic wrote:
> I am newbie in this.  Anybody done it?
> 
> Any lead is appreciated.

please do not hijack threads.  do not just pick a random e-mail and hit 
"reply".  start a new one from scratch.

as for your question, check out the latest git.  yaffs2 is already in u-boot 
and has been for some time.
-mike
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[U-Boot] Porting YAFFS2 to U-boot

[Charles Manning]

Bud

Last time I looked, the yaffs code in u-boot is pretty old and I would 
recommend refreshing it.

-- Charles


On Friday 03 February 2012 10:40:45 Bud Miljkovic wrote:
> I am newbie in this.  Anybody done it?
>
> Any lead is appreciated.
>
> Cheers,
> Bud Miljkovic
>
> -----Original Message-----
> From: Marek Vasut [mailto:marek.vasut at gmail.com]
> Sent: Wednesday, 1 February 2012 11:58 p.m.
> To: Wolfgang Denk
> Cc: u-boot at lists.denx.de; Bud Miljkovic
> Subject: Re: [U-Boot] Can u-Boot Ran from RAM?
>
> > Dear Marek Vasut,
> >
> > In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
> > > > On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > > > > While getting acquainted with possible u-Boot development
>
> issues, I
>
> > > > > read FAQ "14.2.1.  Can U-Boot be configured such that it can be
> > > > > started in RAM?" and was puzzled to learn that u-Boot cannot run
> > > > > from RAM.
> > > >
> > > > you misread it.  the question is for people who have loaded
>
> u-boot, and
>
> > > > then want to load another copy of u-boot into ram and then execute
>
> that
>
> > > > directly.
> > > >
> > > > so the question is "can u-boot be *started in ram*" and the answer
>
> is
>
> > > > "no".
> > >
> > > The answer is "yes if you know how to do it" ;-)
> >
> > The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
> > and start it.  You must prepare a _special_ image which omits all the
> > initializations that are normally included.
>
> You can on PXA ;-)
>
> > This FAQ addresses the situation where people want to load and run
> > their _normal_ images before burning these to flash.  And this CANNOT
> > be done like that.
>
> You're certainly right this is true for general case, but there are
> special
> cases where you can load u-boot from u-boot without any harm (PXA is the
>
> example).
>
> > Best regards,
> >
> > Wolfgang Denk
>
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

[U-Boot] Porting YAFFS2 to U-boot

[Peter Barada]

I have a pile of changes to u-boot that make yaffs work w/mtdparts (I.e. "ymount /<partition>" looks through mtdparts to find start/end blocks, etc) that works in u-boot-2011.06), and want to refresh that for a current u-boot, but it's gonna take time to get it into acceptable shape for submission.

If anyone wants the raw changes to get a head start I'm happy to pass them along...

Splat-fingered from my iPhone

On Feb 2, 2012, at 5:20 PM, "Charles Manning" <manningc2@actrix.gen.nz> wrote:

> Bud
> 
> Last time I looked, the yaffs code in u-boot is pretty old and I would 
> recommend refreshing it.
> 
> -- Charles
> 
> 
> On Friday 03 February 2012 10:40:45 Bud Miljkovic wrote:
>> I am newbie in this.  Anybody done it?
>> 
>> Any lead is appreciated.
>> 
>> Cheers,
>> Bud Miljkovic
>> 
>> -----Original Message-----
>> From: Marek Vasut [mailto:marek.vasut at gmail.com]
>> Sent: Wednesday, 1 February 2012 11:58 p.m.
>> To: Wolfgang Denk
>> Cc: u-boot at lists.denx.de; Bud Miljkovic
>> Subject: Re: [U-Boot] Can u-Boot Ran from RAM?
>> 
>>> Dear Marek Vasut,
>>> 
>>> In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
>>>>> On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
>>>>>> While getting acquainted with possible u-Boot development
>> 
>> issues, I
>> 
>>>>>> read FAQ "14.2.1.  Can U-Boot be configured such that it can be
>>>>>> started in RAM?" and was puzzled to learn that u-Boot cannot run
>>>>>> from RAM.
>>>>> 
>>>>> you misread it.  the question is for people who have loaded
>> 
>> u-boot, and
>> 
>>>>> then want to load another copy of u-boot into ram and then execute
>> 
>> that
>> 
>>>>> directly.
>>>>> 
>>>>> so the question is "can u-boot be *started in ram*" and the answer
>> 
>> is
>> 
>>>>> "no".
>>>> 
>>>> The answer is "yes if you know how to do it" ;-)
>>> 
>>> The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
>>> and start it.  You must prepare a _special_ image which omits all the
>>> initializations that are normally included.
>> 
>> You can on PXA ;-)
>> 
>>> This FAQ addresses the situation where people want to load and run
>>> their _normal_ images before burning these to flash.  And this CANNOT
>>> be done like that.
>> 
>> You're certainly right this is true for general case, but there are
>> special
>> cases where you can load u-boot from u-boot without any harm (PXA is the
>> 
>> example).
>> 
>>> Best regards,
>>> 
>>> Wolfgang Denk
>> 
>> _______________________________________________
>> U-Boot mailing list
>> U-Boot at lists.denx.de
>> http://lists.denx.de/mailman/listinfo/u-boot
> 
> 
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

[U-Boot] Porting YAFFS2 to U-boot

[Wolfgang Denk]

Dear Charles Manning,

In message <201202031119.57323.manningc2@actrix.gen.nz> you wrote:
> 
> Last time I looked, the yaffs code in u-boot is pretty old and I would 
> recommend refreshing it.

Patches are welcome!

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
It seems intuitively obvious to me, which  means  that  it  might  be
wrong.                                                 -- Chris Torek

[U-Boot] Can u-Boot Ran from RAM?

[Bud Miljkovic]

Here is another go on this issue!

The following is a response from Freescale technical support with my
questions inserted:
----------> 
The "initial bootloader" code (including IVT, DCD and application code
itself) should be very small to fit into 4Kb space that is read out from
NAND Flash during the first stage of NAND boot. The typical use case of
NAND boot in i.MX53-based systems is as follows.
1. Internal BootROM code finds the valid initial 4Kb space within NAND
Flash memory and loads it into the NAND Flash Controller's (NFC's) RAM
buffer.

2. Internal BootROM code finds a valid IVT in just loaded data,
processes it, finds DCD and performs the initialization of integrated
peripherals (typically, SDRAM controller, IOMUX and, if required, other
peripherals) according to it.

3. Internal BootROM code finds an application code (typically, "initial
bootloader"), copies it into target memory (typically SDRAM) and passes
control to it.

4. The "initial bootloader" code copies a main bootloader (e.g. uBoot)
from NAND Flash to SDRAM and passes control to it.
Bud_Q1> This is issue:  will the uBoot run correctly if it starts from
SDRAM as suggested?

Bud_Q2> Based on my understanding of how the u-Boot runs, the "initial
bootloader" should just pass control to the u-Boot in NAND?  This would
cause for all integrated peripherals to re-initialized but should not be
a problem.

5. The boot process continues under the control of main bootloader.

So, at the moment when main bootloader (uBoot) starts working, most of
the primarily required integrated peripherals (SDRAM controller, NAND
Flash controller) are already initialized and working, so, a main
bootloader has no need to re-initialize them.
Bud_Q3> Is there maybe a version of a u-Boot that skips initialization
phase, i.e. just relocates itself to RAM?

<------------

Can you please respond to my questions?
-bud


-----Original Message-----
From: Marek Vasut [mailto:marek.vasut at gmail.com] 
Sent: Wednesday, 1 February 2012 11:58 p.m.
To: Wolfgang Denk
Cc: u-boot@lists.denx.de; Bud Miljkovic
Subject: Re: [U-Boot] Can u-Boot Ran from RAM?

> Dear Marek Vasut,
> 
> In message <201202011111.09465.marek.vasut@gmail.com> you wrote:
> > > On Monday 30 January 2012 23:07:05 Bud Miljkovic wrote:
> > > > While getting acquainted with possible u-Boot development
issues, I
> > > > read FAQ "14.2.1.  Can U-Boot be configured such that it can be
> > > > started in RAM?" and was puzzled to learn that u-Boot cannot run
> > > > from RAM.
> > > 
> > > you misread it.  the question is for people who have loaded
u-boot, and
> > > then want to load another copy of u-boot into ram and then execute
that
> > > directly.
> > > 
> > > so the question is "can u-boot be *started in ram*" and the answer
is
> > > "no".
> > 
> > The answer is "yes if you know how to do it" ;-)
> 
> The answer is "NO".  You cannot load the _normal_ U-Boot image to RAM
> and start it.  You must prepare a _special_ image which omits all the
> initializations that are normally included.

You can on PXA ;-)
> 
> This FAQ addresses the situation where people want to load and run
> their _normal_ images before burning these to flash.  And this CANNOT
> be done like that.

You're certainly right this is true for general case, but there are
special 
cases where you can load u-boot from u-boot without any harm (PXA is the

example).

> 
> Best regards,
> 
> Wolfgang Denk