Making partitions questions.

Making partitions questions.

[Alexandr Andreev]

Hi,
I have some questions about making partitions on Intel CFI chips.

1. I read mtd-jffs-HOWTO, and found that can't launch fdisk and create
partitions on my flash dynamically. It have to be created and compiled in a
lowlevel driver. What is the reason? Is anybody working at it?

2. I wish to have several partitions on my flash. Can i have partitions 
with
different filesystems on it? I mean one partition with FTL & ext2 and other
with JFFS2 for example.

Thanks in advance.

Re: Making partitions questions.

[Abraham vd Merwe]

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Hi Alexandr!

> 1. I read mtd-jffs-HOWTO, and found that can't launch fdisk and create
> partitions on my flash dynamically. It have to be created and compiled in a
> lowlevel driver. What is the reason? Is anybody working at it?

The reason why this have to be done is that the mtd partition driver needs
to know the partition information before it can register those partitions as
devices (it basically just goes and setup MTD structures for each partition
and register them the normal way).

In order to actually make a userland utility you'd have to implement a
system call to actually send the info to the partition driver which will
have to reregister the devices. Not all that difficult, but I don't think
anybody is working on it right now.

> 2. I wish to have several partitions on my flash. Can i have partitions 
> with
> different filesystems on it? I mean one partition with FTL & ext2 and other
> with JFFS2 for example.

Yes. As long as you compile your kernel with MTD block device support it,
you can put anything on those block devices. I wouldn't use ext2 on flash
tho since it's not optimised for flash - jffs2 is definitely your best bet.

-- 

Regards
 Abraham

Today is National Existential Ennui Awareness Day.

__________________________________________________________
 Abraham vd Merwe - 2d3D, Inc.

 Device Driver Development, Outsourcing, Embedded Systems

  Cell: +27 82 565 4451         Snailmail:
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Re: Making partitions questions.

[David Woodhouse]

abraham@2d3d.co.za said:
>  In order to actually make a userland utility you'd have to implement
> a system call to actually send the info to the partition driver which
> will have to reregister the devices. Not all that difficult, but I
> don't think anybody is working on it right now.

You don't necessarily need to be able to change them at runtime. We already 
support a few methods of storing partitioning information on the medium 
rather than hard-coding it in the mapping driver. We can grok RedBoot FIS 
tables, Compaq bootldr partitions, and also the ARM Firmware Suite layout.


abraham@2d3d.co.za said:
>  Yes. As long as you compile your kernel with MTD block device support
> it, you can put anything on those block devices. I wouldn't use ext2
> on flash tho since it's not optimised for flash - jffs2 is definitely
> your best bet. 

He said ext2 on FTL. That's sane, but possibly not legal, depending on 
whether software patents are enforceable in your part of the world.

--
dwmw2

Re: Making partitions questions.

[Alexandr Andreev]

David Woodhouse wrote:

>  You don't necessarily need to be able to change them at runtime. We already 
>  support a few methods of storing partitioning information on the medium 
>  rather than hard-coding it in the mapping driver. We can grok RedBoot FIS 
>  tables, Compaq bootldr partitions, and also the ARM Firmware Suite layout.

I need to be able to change it while development. I need to create and modify 
partitions dynamically, because the size of partitions can be variable during 
development stage. I want to have one partition for the kernel with no 
filesystem on it at all, the second partition for ext2 filesystem with read 
only accesses, and the third for the JFFS2 full functional filesystem. 

Is there any common userland utils for creating RedBoot, Compaq or ARM 
partitions? 

Abraham vd Merwe wrote:

>  The reason why this have to be done is that the mtd partition driver needs
>  to know the partition information before it can register those partitions as
>  devices (it basically just goes and setup MTD structures for each partition
>  and register them the normal way).

Fine. But, why we can't just use MBR and common IDE partition table instead of 
RedBoot, Compaq, ARM and other specific partitions? 

>  In order to actually make a userland utility you'd have to implement a
>  system call to actually send the info to the partition driver which will
>  have to reregister the devices. Not all that difficult, but I don't think
>  anybody is working on it right now.

I guess, we can do the similar to IDE things. And it allows us to use 
habitual
fdisk utility with flash. But it also means, that whole flash device 
have to
be registered ( /dev/mtdblocka for example ). Is it worth while? Is this 
work
usable?