[U-Boot-Users] NAND "bad block" support

[U-Boot-Users] NAND "bad block" support

[Shai Lifshitz]

how does the U-Boot solve the "bad block" problem in the NAND flash 
memory?
1) does the U-Boot have support to 'bad-block table'? If it does, then how 
do I activate it?
2) does the U-Boot work with JFFS2 (that handles 'bad blocks')?

Sincerely
Shai Lifshitz
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[U-Boot-Users] NAND "bad block" support

[Stefan Roese]

On Sunday 05 August 2007, Shai Lifshitz wrote:
> how does the U-Boot solve the "bad block" problem in the NAND flash
> memory?

Yes, U-Boot NAND driver is bad block aware (would be worthless without).

> 1) does the U-Boot have support to 'bad-block table'? If it does, then how
> do I activate it?

No, the bad-block-table is not supported right now. Would be nice extension 
though.

> 2) does the U-Boot work with JFFS2 (that handles 'bad blocks')?

Yes.

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
=====================================================================

[U-Boot-Users] NAND "bad block" support

[Shai Lifshitz]

Hi Stefan

Thanks for your answer

I am planning to use the U-Boot to load the Linux operating system that is 
stored on a NAND flash.

The UBoot main role (beside other tasks) is to load the linux kernel and 
file-system from the NAND flash to the RAM, and start the linux. 
Another role of UBoot is to get the kernel and file-system from the 
ethernet, and burn it to the NAND flash.

What is the preferred way to treat the "bad block" problem in writing (not 
writing to bad blocks, and checking the status after programming/erasing) 
and reading (jumping over bad blocks).

1) Does normal read/write coop with these issues?

2) In the NAND documentation it says that the "shipped bad blocks" have to 
be checked prior to any erase operations. Does the UBoot leave the bad 
blocks untouched during the erase operation?

3) Do you recommend to use JFFS2 file-system just to save/read the 
kernel/file-system images?

Sincerely

Shai Lifshitz
email: shail at visonic.com





Stefan Roese <sr@denx.de>
Sent by: u-boot-users-bounces at lists.sourceforge.net
08/06/2007 02:12 PM
 
        To:     u-boot-users at lists.sourceforge.net
        cc:     Shai Lifshitz <ShaiL@visonic.com>
        Subject:        Re: [U-Boot-Users] NAND "bad block" support


On Sunday 05 August 2007, Shai Lifshitz wrote:
> how does the U-Boot solve the "bad block" problem in the NAND flash
> memory?

Yes, U-Boot NAND driver is bad block aware (would be worthless without).

> 1) does the U-Boot have support to 'bad-block table'? If it does, then 
how
> do I activate it?

No, the bad-block-table is not supported right now. Would be nice 
extension 
though.

> 2) does the U-Boot work with JFFS2 (that handles 'bad blocks')?

Yes.

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
=====================================================================

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[U-Boot-Users] NAND "bad block" support

[Stefan Roese]

Hi Shai,

On Monday 06 August 2007, Shai Lifshitz wrote:
> I am planning to use the U-Boot to load the Linux operating system that is
> stored on a NAND flash.
>
> The UBoot main role (beside other tasks) is to load the linux kernel and
> file-system from the NAND flash to the RAM, and start the linux.
> Another role of UBoot is to get the kernel and file-system from the
> ethernet, and burn it to the NAND flash.

OK, that's what U-Boot is designed for.

> What is the preferred way to treat the "bad block" problem in writing (not
> writing to bad blocks, and checking the status after programming/erasing)
> and reading (jumping over bad blocks).
>
> 1) Does normal read/write coop with these issues?

Yes.

> 2) In the NAND documentation it says that the "shipped bad blocks" have to
> be checked prior to any erase operations. Does the UBoot leave the bad
> blocks untouched during the erase operation?

Yes.

> 3) Do you recommend to use JFFS2 file-system just to save/read the
> kernel/file-system images?

The kernel doesn't need to be saved in a filesystem at all. I would reserve 
one flash partition for it and read/write it from there. Some goes for the 
root filesystem if you don't have to write to it from Linux. You could use 
cramfs, romfs, initrd etc.

BTW: Please note that U-Boot "only" supports JFFS2 read operations. For 
writing to NAND (and NOR...) you will have to write raw data to the chip. But 
that's what the interface is designed for and what is already working in lots 
of projects.

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
=====================================================================