Is there really need to build Block Device Emulation over UBI?

Is there really need to build Block Device Emulation over UBI?

[Nancy]

Hi,
   Is there really need to build Block Device Emulation over UBI? Why
can't use the mtd_blkdev.c and mtdblock.c directly?
   Thanks to gluebi, make UBI and MTD become one. More interesting
thing is,  volume can be treat like a mtd partition. mtdblock.c do not
have wear-leveling and bad block management mechanism but UBI has.
gluebi make all those functions mix together right?
   I have tried, and it work.

Re: Is there really need to build Block Device Emulation over UBI?

[Artem Bityutskiy]

On Thu, 2008-01-24 at 11:13 +0800, Nancy wrote:
> Hi,
>    Is there really need to build Block Device Emulation over UBI? Why
> can't use the mtd_blkdev.c and mtdblock.c directly?
>    Thanks to gluebi, make UBI and MTD become one. More interesting
> thing is,  volume can be treat like a mtd partition. mtdblock.c do not
> have wear-leveling and bad block management mechanism but UBI has.
> gluebi make all those functions mix together right?
>    I have tried, and it work.

The problem with mtdblock is that when it needs to change an eraseblock,
it reads it, erases, then writes new data to it, which would cause data
loss in case of an unclean reboot.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)

Re: Is there really need to build Block Device Emulation over UBI?

[Nancy]

> The problem with mtdblock is that when it needs to change an eraseblock,
> it reads it, erases, then writes new data to it, which would cause data
> loss in case of an unclean reboot.

If I can delay  the erase operation, then it perfect works?  when
change a eraseblock, reads it(from old mapped PEB) , then writes new
data to it(new mapped PEB), finally erase the old mapped PEB.

How about that?


--
Best Wishes,
Nancy

Re: Is there really need to build Block Device Emulation over UBI?

[Artem Bityutskiy]

On Thu, 2008-01-24 at 16:24 +0800, Nancy wrote:
> > The problem with mtdblock is that when it needs to change an eraseblock,
> > it reads it, erases, then writes new data to it, which would cause data
> > loss in case of an unclean reboot.
> 
> If I can delay  the erase operation, then it perfect works?  when
> change a eraseblock, reads it(from old mapped PEB) , then writes new
> data to it(new mapped PEB), finally erase the old mapped PEB.
> 
> How about that?

Yes, this is OK, but mtdblock does not do this. Here I wrote about how
to create a simple FTL layer over UBI:

http://lists.infradead.org/pipermail/linux-mtd/2008-January/020381.html

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)

Re: Is there really need to build Block Device Emulation over UBI?

[Artem Bityutskiy]

On Thu, 2008-01-24 at 11:13 +0800, Nancy wrote:
> Hi,
>    Is there really need to build Block Device Emulation over UBI? Why
> can't use the mtd_blkdev.c and mtdblock.c directly?
>    Thanks to gluebi, make UBI and MTD become one. More interesting
> thing is,  volume can be treat like a mtd partition. mtdblock.c do not
> have wear-leveling and bad block management mechanism but UBI has.
> gluebi make all those functions mix together right?
>    I have tried, and it work.

Frankly, I am very busy now and have no time to review so much code.
Please, communicate via the mailing list instead. And please, send
patches instead of whole files.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)