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Bootrom and bad blocks in NAND

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Participant
Posts: 36
Registered: ‎05-18-2016
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Bootrom and bad blocks in NAND

How, if at all, bootrom handles bad blocks in NAND flash during boot process? Does it read bad block table, or checks information in OOB memory of first page in block?


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Xilinx Employee
Posts: 117
Registered: ‎10-30-2017

Re: Bootrom and bad blocks in NAND

Hi  Saleksin,

 

The BootROM manages bad blocks in the following ways:
• It looks for a bad block table (BBT) in the last four blocks of the NAND flash device.
• It supports a primary and secondary BBT with versioning allowing safe software updates.
• If a BBT is not present, the BootROM scans the flash reading the out-of-band (OOB) information
to determine the locations of bad blocks.
• The BootROM only performs read operations – it does not write to the flash.
While reading from NAND, the BootROM skips blocks that are marked as bad in the BBT, or in the
OOB information if a BBT does not exist.

 

For more information please read 6.3.5 NAND BOOT in ug585.

 

Best Regards,
Srikanth
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Xilinx Employee
Posts: 117
Registered: ‎10-30-2017

Re: Bootrom and bad blocks in NAND

Hi  Saleksin,

 

The BootROM manages bad blocks in the following ways:
• It looks for a bad block table (BBT) in the last four blocks of the NAND flash device.
• It supports a primary and secondary BBT with versioning allowing safe software updates.
• If a BBT is not present, the BootROM scans the flash reading the out-of-band (OOB) information
to determine the locations of bad blocks.
• The BootROM only performs read operations – it does not write to the flash.
While reading from NAND, the BootROM skips blocks that are marked as bad in the BBT, or in the
OOB information if a BBT does not exist.

 

For more information please read 6.3.5 NAND BOOT in ug585.

 

Best Regards,
Srikanth
----------------------------------------------------------------------------------------------
Kindly note- Please mark the Answer as "Accept as solution" if information provided is helpful.

Give Kudos to a post which you think is helpful and reply oriented.

 

Participant
Posts: 36
Registered: ‎05-18-2016

Re: Bootrom and bad blocks in NAND

Many thanks!