[U-Boot] RFC: i.MX6 write U-Boot to NAND

[U-Boot] RFC: i.MX6 write U-Boot to NAND

[Sergey Kubushyn]

Hi everybody,

It looks like using kobs-ng utility is the only way to make a bootable NAND
for i.MX6 and their siblings. There might be other utilities I'm not aware
of but that doesn't change anything -- you need Linux (or whatever that
utility runs on) running on your board to create and write all those FCB and
other parts onto a virgin raw NAND device.

This makes initial programming a cumbersome and complicated operation. One
can not program NAND on a development machine as it is easy to do with e.g.
SD Card -- the OS must run on the same board where that NAND is because NAND
is not removable.

It is possible, of course, to assemble something on an SD Card and use that
to program NAND but that assumes there is an SD Card slot on a target system
and some means to tell it to boot off of SD Card. However it is not always a
case -- there might be boards with NAND as only storage device available.
That leaves only Serial/USB boot as only options for initial boot on a
virgin board. However it does not provide means for writing the NAND U-Boot
into actual NAND.

There are many different varieties of NAND chips so those FCB and other
structures are not generic i.e. they can not be defined beforehead and just
prepended to the actual U-Boot image. Even if we have made those a
configuration parameters there are still bad block tables that are chip
specific so they should be discovered first i.e. FCB should be built
dynamically based on NAND scanning results.

Sure, one can write a custom first stage SPL that would've booted the actual
U-Boot via the same Serial/USB interface and run it but then what? Let's
assume the target board doesn't have ethernet so it would make it impossible
to mount rootfs over NFS and no other storage devices available. It is still
possible to load Linux kernel and bare minimal rootfs in initramfs image but
that's a lot of serial downloading just for initializing NAND...

It would be nice to have a U-Boot command that would've allowed initial NAND
setup and writing NAND U-Boot image to it properly updating the headers.

There might be other ways to do this that I might've overlooked...

Does anybody knows a ready-made solution or works on something suitable for
this purpose? I don't want to re-invent the wheel starting my own solution
so it would've been good to hear from other guys who might've solved this
dilemma.

Any thoughts?

---
******************************************************************
*  KSI at home    KOI8 Net  < >  The impossible we do immediately.  *
*  Las Vegas   NV, USA   < >  Miracles require 24-hour notice.   *
******************************************************************

[U-Boot] RFC: i.MX6 write U-Boot to NAND

[Heiko Schocher]

Hello Sergey,

add Stefano to Cc as he is the imx6 custodian,

Am 25.04.2016 um 22:29 schrieb Sergey Kubushyn:
> Hi everybody,
>
> It looks like using kobs-ng utility is the only way to make a bootable NAND
> for i.MX6 and their siblings. There might be other utilities I'm not aware
> of but that doesn't change anything -- you need Linux (or whatever that
> utility runs on) running on your board to create and write all those FCB and
> other parts onto a virgin raw NAND device.

Yes, I stumbled over that too recently ...

> This makes initial programming a cumbersome and complicated operation. One
> can not program NAND on a development machine as it is easy to do with e.g.
> SD Card -- the OS must run on the same board where that NAND is because NAND
> is not removable.
>
> It is possible, of course, to assemble something on an SD Card and use that
> to program NAND but that assumes there is an SD Card slot on a target system
> and some means to tell it to boot off of SD Card. However it is not always a
> case -- there might be boards with NAND as only storage device available.
> That leaves only Serial/USB boot as only options for initial boot on a
> virgin board. However it does not provide means for writing the NAND U-Boot
> into actual NAND.
>
> There are many different varieties of NAND chips so those FCB and other
> structures are not generic i.e. they can not be defined beforehead and just
> prepended to the actual U-Boot image. Even if we have made those a
> configuration parameters there are still bad block tables that are chip
> specific so they should be discovered first i.e. FCB should be built
> dynamically based on NAND scanning results.
>
> Sure, one can write a custom first stage SPL that would've booted the actual
> U-Boot via the same Serial/USB interface and run it but then what? Let's
> assume the target board doesn't have ethernet so it would make it impossible
> to mount rootfs over NFS and no other storage devices available. It is still
> possible to load Linux kernel and bare minimal rootfs in initramfs image but
> that's a lot of serial downloading just for initializing NAND...
>
> It would be nice to have a U-Boot command that would've allowed initial NAND
> setup and writing NAND U-Boot image to it properly updating the headers.

Yes, that would be great!

> There might be other ways to do this that I might've overlooked...
>
> Does anybody knows a ready-made solution or works on something suitable for
> this purpose? I don't want to re-invent the wheel starting my own solution
> so it would've been good to hear from other guys who might've solved this
> dilemma.

Sorry, I do not know another way.

> Any thoughts?

I think, an U-Boot command which writes the headers into the nand would
be a good thing.

tools/imximage.c is may the wrong place, as the infos in FCB and DBBT
are dependend on the boards nand.

bye,
Heiko
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

[U-Boot] RFC: i.MX6 write U-Boot to NAND

[Stefan Roese]

Hi Sergey, Hi Heiko,

On 26.04.2016 07:43, Heiko Schocher wrote:
> add Stefano to Cc as he is the imx6 custodian,
>
> Am 25.04.2016 um 22:29 schrieb Sergey Kubushyn:
>> Hi everybody,
>>
>> It looks like using kobs-ng utility is the only way to make a bootable
>> NAND
>> for i.MX6 and their siblings. There might be other utilities I'm not
>> aware
>> of but that doesn't change anything -- you need Linux (or whatever that
>> utility runs on) running on your board to create and write all those
>> FCB and
>> other parts onto a virgin raw NAND device.
>
> Yes, I stumbled over that too recently ...
>
>> This makes initial programming a cumbersome and complicated operation.
>> One
>> can not program NAND on a development machine as it is easy to do with
>> e.g.
>> SD Card -- the OS must run on the same board where that NAND is
>> because NAND
>> is not removable.
>>
>> It is possible, of course, to assemble something on an SD Card and use
>> that
>> to program NAND but that assumes there is an SD Card slot on a target
>> system
>> and some means to tell it to boot off of SD Card. However it is not
>> always a
>> case -- there might be boards with NAND as only storage device available.
>> That leaves only Serial/USB boot as only options for initial boot on a
>> virgin board. However it does not provide means for writing the NAND
>> U-Boot
>> into actual NAND.
>>
>> There are many different varieties of NAND chips so those FCB and other
>> structures are not generic i.e. they can not be defined beforehead and
>> just
>> prepended to the actual U-Boot image. Even if we have made those a
>> configuration parameters there are still bad block tables that are chip
>> specific so they should be discovered first i.e. FCB should be built
>> dynamically based on NAND scanning results.
>>
>> Sure, one can write a custom first stage SPL that would've booted the
>> actual
>> U-Boot via the same Serial/USB interface and run it but then what? Let's
>> assume the target board doesn't have ethernet so it would make it
>> impossible
>> to mount rootfs over NFS and no other storage devices available. It is
>> still
>> possible to load Linux kernel and bare minimal rootfs in initramfs
>> image but
>> that's a lot of serial downloading just for initializing NAND...
>>
>> It would be nice to have a U-Boot command that would've allowed
>> initial NAND
>> setup and writing NAND U-Boot image to it properly updating the headers.
>
> Yes, that would be great!
>
>> There might be other ways to do this that I might've overlooked...
>>
>> Does anybody knows a ready-made solution or works on something
>> suitable for
>> this purpose? I don't want to re-invent the wheel starting my own
>> solution
>> so it would've been good to hear from other guys who might've solved this
>> dilemma.
>
> Sorry, I do not know another way.
>
>> Any thoughts?
>
> I think, an U-Boot command which writes the headers into the nand would
> be a good thing.
>
> tools/imximage.c is may the wrong place, as the infos in FCB and DBBT
> are dependend on the boards nand.

I've missed such a tool a few years ago while porting U-Boot & Linux
to a i.MX6 based NAND booting board as well. And noticed since then
that barebox has included such a tool:

http://lists.infradead.org/pipermail/barebox/2014-March/018202.html

Perhaps its not too much work to port this tool over to U-Boot?
Just an idea...

Thanks,
Stefan

[U-Boot] RFC: i.MX6 write U-Boot to NAND

[Sergey Kubushyn]

On Tue, 26 Apr 2016, Stefan Roese wrote:

OK, if nobody worked on this so far I'll bite the bullet -- working on a
NAND boot only i.mx6 module right now at my day job and need manufacturing
tools for production. Just didn't want to re-invent the wheel and mess with
somebody's else work...

Will try to submit a patch by the end of week if nothing come into the way.

> Hi Sergey, Hi Heiko,
>
> On 26.04.2016 07:43, Heiko Schocher wrote:
>>  add Stefano to Cc as he is the imx6 custodian,
>>
>>  Am 25.04.2016 um 22:29 schrieb Sergey Kubushyn:
>> >  Hi everybody,
>> > 
>> >  It looks like using kobs-ng utility is the only way to make a bootable
>> >  NAND
>> >  for i.MX6 and their siblings. There might be other utilities I'm not
>> >  aware
>> >  of but that doesn't change anything -- you need Linux (or whatever that
>> >  utility runs on) running on your board to create and write all those
>> >  FCB and
>> >  other parts onto a virgin raw NAND device.
>>
>>  Yes, I stumbled over that too recently ...
>> 
>> >  This makes initial programming a cumbersome and complicated operation.
>> >  One
>> >  can not program NAND on a development machine as it is easy to do with
>> >  e.g.
>> >  SD Card -- the OS must run on the same board where that NAND is
>> >  because NAND
>> >  is not removable.
>> > 
>> >  It is possible, of course, to assemble something on an SD Card and use
>> >  that
>> >  to program NAND but that assumes there is an SD Card slot on a target
>> >  system
>> >  and some means to tell it to boot off of SD Card. However it is not
>> >  always a
>> >  case -- there might be boards with NAND as only storage device 
>> >  available.
>> >  That leaves only Serial/USB boot as only options for initial boot on a
>> >  virgin board. However it does not provide means for writing the NAND
>> >  U-Boot
>> >  into actual NAND.
>> > 
>> >  There are many different varieties of NAND chips so those FCB and other
>> >  structures are not generic i.e. they can not be defined beforehead and
>> >  just
>> >  prepended to the actual U-Boot image. Even if we have made those a
>> >  configuration parameters there are still bad block tables that are chip
>> >  specific so they should be discovered first i.e. FCB should be built
>> >  dynamically based on NAND scanning results.
>> > 
>> >  Sure, one can write a custom first stage SPL that would've booted the
>> >  actual
>> >  U-Boot via the same Serial/USB interface and run it but then what? Let's
>> >  assume the target board doesn't have ethernet so it would make it
>> >  impossible
>> >  to mount rootfs over NFS and no other storage devices available. It is
>> >  still
>> >  possible to load Linux kernel and bare minimal rootfs in initramfs
>> >  image but
>> >  that's a lot of serial downloading just for initializing NAND...
>> > 
>> >  It would be nice to have a U-Boot command that would've allowed
>> >  initial NAND
>> >  setup and writing NAND U-Boot image to it properly updating the headers.
>>
>>  Yes, that would be great!
>> 
>> >  There might be other ways to do this that I might've overlooked...
>> > 
>> >  Does anybody knows a ready-made solution or works on something
>> >  suitable for
>> >  this purpose? I don't want to re-invent the wheel starting my own
>> >  solution
>> >  so it would've been good to hear from other guys who might've solved 
>> >  this
>> >  dilemma.
>>
>>  Sorry, I do not know another way.
>> 
>> >  Any thoughts?
>>
>>  I think, an U-Boot command which writes the headers into the nand would
>>  be a good thing.
>>
>>  tools/imximage.c is may the wrong place, as the infos in FCB and DBBT
>>  are dependend on the boards nand.
>
> I've missed such a tool a few years ago while porting U-Boot & Linux
> to a i.MX6 based NAND booting board as well. And noticed since then
> that barebox has included such a tool:
>
> http://lists.infradead.org/pipermail/barebox/2014-March/018202.html
>
> Perhaps its not too much work to port this tool over to U-Boot?
> Just an idea...
>
> Thanks,
> Stefan
>
>

---
******************************************************************
*  KSI at home    KOI8 Net  < >  The impossible we do immediately.  *
*  Las Vegas   NV, USA   < >  Miracles require 24-hour notice.   *
******************************************************************

[U-Boot] RFC: i.MX6 write U-Boot to NAND

[Stefan Roese]

On 26.04.2016 08:58, Sergey Kubushyn wrote:
> On Tue, 26 Apr 2016, Stefan Roese wrote:
>
> OK, if nobody worked on this so far I'll bite the bullet -- working on a
> NAND boot only i.mx6 module right now at my day job and need manufacturing
> tools for production. Just didn't want to re-invent the wheel and mess with
> somebody's else work...
>
> Will try to submit a patch by the end of week if nothing come into the way.

That would be just great. Thank you very much for tackling this
task.

Thanks,
Stefan