Changing eMMC boot partition size

Changing eMMC boot partition size

[Philip Oberfichtner]

Hi everybody,

I have a question regarding changing the eMMC boot partition size.
According the the JEDEC eMMC spec it is read-only (BOOT_SIZE_MULT
register).

But we still have mmc_boot_partition_size_change() in
drivers/mmc/mmc_boot.c. It contains the comment

/* Only use this command for raw EMMC moviNAND. Enter backdoor mode */

What is moviNAND? My research pointed me to Samsung products only. So
is changing the boot partition size vendor specific or can it be used
more generally?

To be specific, I use the Kioxia THGBMJG6C1LBAB7 eMMC chip.


Thanks and best regards,
Philip Oberfichtner

Re: Changing eMMC boot partition size

[Tom Rini]

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On Tue, Nov 08, 2022 at 06:34:18PM +0100, Philip Oberfichtner wrote:
> Hi everybody,
> 
> I have a question regarding changing the eMMC boot partition size.
> According the the JEDEC eMMC spec it is read-only (BOOT_SIZE_MULT
> register).
> 
> But we still have mmc_boot_partition_size_change() in
> drivers/mmc/mmc_boot.c. It contains the comment
> 
> /* Only use this command for raw EMMC moviNAND. Enter backdoor mode */
> 
> What is moviNAND? My research pointed me to Samsung products only. So
> is changing the boot partition size vendor specific or can it be used
> more generally?
> 
> To be specific, I use the Kioxia THGBMJG6C1LBAB7 eMMC chip.

Yes, moviNAND was some Samsung technology that may or may not still be
used on some platforms. And yes, some eMMC parts do allow for boot
partitions to be resized but such information is often under NDA, so
contacting the hardware vendor or looking for eMMC chip documentation
may be helpful here.

-- 
Tom

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Re: Changing eMMC boot partition size

[Jaehoon Chung]

Hi,

On 11/9/22 03:30, Tom Rini wrote:
> On Tue, Nov 08, 2022 at 06:34:18PM +0100, Philip Oberfichtner wrote:
>> Hi everybody,
>>
>> I have a question regarding changing the eMMC boot partition size.
>> According the the JEDEC eMMC spec it is read-only (BOOT_SIZE_MULT
>> register).
>>
>> But we still have mmc_boot_partition_size_change() in
>> drivers/mmc/mmc_boot.c. It contains the comment
>>
>> /* Only use this command for raw EMMC moviNAND. Enter backdoor mode */
>>
>> What is moviNAND? My research pointed me to Samsung products only. So
>> is changing the boot partition size vendor specific or can it be used
>> more generally?
>>
>> To be specific, I use the Kioxia THGBMJG6C1LBAB7 eMMC chip.
> 
> Yes, moviNAND was some Samsung technology that may or may not still be
> used on some platforms. And yes, some eMMC parts do allow for boot
> partitions to be resized but such information is often under NDA, so
> contacting the hardware vendor or looking for eMMC chip documentation
> may be helpful here.

Thanks for replying this. As like Tom's comment, eMMC that is manufactured from Samsung was called MoviNand.
It's used with Reserved Command for manufacturer. 
So If you want to change your eMMC's boot partition size,  you need to check Kioxiz documentation.

Best Regards,
Jaehoon Chung

>