Re: [PATCH] mtd: fix size in mtd_info_user to support 64-bit

[Rob Landley]

On 7/16/21 4:48 AM, Miquel Raynal wrote:
> Hi Miaohe,
> 
> Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote on Fri, 16 Jul 2021 09:42:19
> +0800:
> 
>> On 2021/7/16 7:02, Miquel Raynal wrote:
>> > Hi Miaohe,
>> > 
>> > Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote on Thu, 8 Jul 2021 21:13:59
>> > +0800:
>> >   
>> >> From: Feilong Lin <linfeilong@xxxxxxxxxx>
>> >>
>> >> The size in struct mtd_info_user is 32-bit, which will cause errors
>> >> when obtaining the size of large-capacity MTD devices, such as TLC
>> >> NAND FLASH-2048Gb.  
>> > 
>> > Besides the fact that such devices are far from being supported by the
>> > Linux kernel, this change would basically break userspace, it cannot
>> > enter as-is...
>> >   
>> 
>> I see. Many thanks for your reply! We're working with these large-capacity
>> MTD devices now, any suggestion to work around this?
> 
> The only way is to create a second UAPI.

Twelve years ago a patch was submitted to add a 64 bit MTD api:

  https://lwn.net/Articles/326418/

But for some reason they only merged 64 bit erase:

  https://github.com/torvalds/linux/commit/0dc54e9f33e2

But NOT the rest of the 64 bit mtd API in the same patch. I've never understood why.

Rob