how can I use MTD partition with large size ( >= 4G bytes)?

how can I use MTD partition with large size ( >= 4G bytes)?

[Tian Jin]

Hi, I want to use NAND flash chips to storage large audio data, the max 
storage size will be 3.6G bytes£¨may be 7G bytes in the future£©, so I have 
to use four 1GB NAND flash chips to make up a single 4GB MTD partition, but 
mtd->size was defined as 32bit integer in MTD driver(linux-2.6.20-rc1), so 
mtd->size just overflowed in function nand_scan_ident():

/* Store the number of chips and calc total size for mtd */
chip->numchips = i;
mtd->size = i * chip->chipsize; // 4 * 40000000 = 0x100000000 = 0xFFFFFFFF + 
0x01

I've tried to modify the data type of mtd->size to usinged long long, but 
kernel can not be compiled successfully£¬Is there any solution for this?

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Re: how can I use MTD partition with large size ( >= 4G bytes)?

[Josh Boyer]

On 3/17/07, Tian Jin <tad2k@msn.com> wrote:
> Hi, I want to use NAND flash chips to storage large audio data, the max
> storage size will be 3.6G bytes£¨may be 7G bytes in the future£(c), so I have
> to use four 1GB NAND flash chips to make up a single 4GB MTD partition, but
> mtd->size was defined as 32bit integer in MTD driver(linux-2.6.20-rc1), so
> mtd->size just overflowed in function nand_scan_ident():
>
> /* Store the number of chips and calc total size for mtd */
> chip->numchips = i;
> mtd->size = i * chip->chipsize; // 4 * 40000000 = 0x100000000 = 0xFFFFFFFF +
> 0x01
>
> I've tried to modify the data type of mtd->size to usinged long long, but
> kernel can not be compiled successfully£¬Is there any solution for this?

Not at the moment.  MTD doesn't support things greater than 4GiB.

josh

Re: how can I use MTD partition with large size ( >= 4G bytes)?

[Artem Bityutskiy]

On Sat, 2007-03-17 at 07:42 -0500, Josh Boyer wrote:
> > I've tried to modify the data type of mtd->size to usinged long long, but
> > kernel can not be compiled successfully£¬Is there any solution for this?
> 
> Not at the moment.  MTD doesn't support things greater than 4GiB.
Yeah.

We should re-work whole MTD and make it use (eraseblock number):(offset
withing eraseblock) addresses, instead of absolute offsets. This implies
changing interfaces. For the in-kernel ones it is not a problem. For the
userspace ones it is. I guess we should just invent new userspace API,
while preserving the old one. This is a great opportunity to dispose of
ancient junk at once.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)