[U-Boot-Users] ROMFS & Uboot.

[U-Boot-Users] ROMFS & Uboot.

[Christophe.LINDHEIMER at fr.thalesgroup.com]

Hi.

It seems that Romfs can be used as Initrd for booting Linux. ( right ?? )
Is this supported by UBoot ?
Has anyone already done this ?

Thanks

Regards

Chris

[U-Boot-Users] ROMFS & Uboot.

[Wolfgang Denk]

In message <D96E2AFA0DF3D211B139009027454948034CBDF3@helios.gnv.tcc.thomson-csf.com> you wrote:
> 
> It seems that Romfs can be used as Initrd for booting Linux. ( right ?? )

Aramdisk is just a block device. You can put any filesystem in it -
minix, ext2, you name it.

> Is this supported by UBoot ?

No. U-Boot has nothing to do with this.

> Has anyone already done this ?

romfs in an initial ramdisk? This makes little sense to me.


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
"You shouldn't make my toaster angry." - Household security explained
in "Johnny Quest"

[U-Boot-Users] ROMFS & Uboot.

[Christophe.LINDHEIMER at fr.thalesgroup.com]

> > It seems that Romfs can be used as Initrd for booting 
> Linux. ( right ?? )
> 
> Aramdisk is just a block device. You can put any filesystem in it -
> minix, ext2, you name it.
> 
> > Is this supported by UBoot ?
> 
> No. U-Boot has nothing to do with this.
> 
> > Has anyone already done this ?
> 
> romfs in an initial ramdisk? This makes little sense to me.
> 

Well, my problem is that I am really short of ram.
So I would like to have my filesystem in flash and keep it in flash.

So I would like to have my root filesytem in flash ( possible ?? ).
romfs seems to be a way to do it.

It think the way to do it it to declare my romfs as initrd ( maybe I am
wrong because initrd is init ram disk and it means that it MUST be a RW
filesystem in RAM ??? )

After reading sources of U Boot it seems that if I put a second parameter at
bootm, it is going to copy the initrd into RAM ( right ? ).
whereas I would like to keep my romfs in flash.

maybe I misunderstand and misuse completly the initrd... Help and hints
welcome...

Chris

[U-Boot-Users] ROMFS & Uboot.

[Wolfgang Denk]

In message <D96E2AFA0DF3D211B139009027454948034CBDF4@helios.gnv.tcc.thomson-csf.com> you wrote:
> 
> Well, my problem is that I am really short of ram.

Easy to fix: add more RAM. RAM is very cheap these days.

> So I would like to have my filesystem in flash and keep it in flash.
> 
> So I would like to have my root filesytem in flash ( possible ?? ).
> romfs seems to be a way to do it.

Of course this is possible. And there  are  many  ways  to  implement
this: romfs, cramfs, jffs2, ...

> It think the way to do it it to declare my romfs as initrd ( maybe I am
> wrong because initrd is init ram disk and it means that it MUST be a RW
> filesystem in RAM ??? )

Right. An initrd is a RAM disk. And a RAM disk is in RAM by definition.

> After reading sources of U Boot it seems that if I put a second parameter at
> bootm, it is going to copy the initrd into RAM ( right ? ).

Not really. Current versions of U-Boot allow to avoid the extra  copy
of  the  ramdisk  image. But the LInux kernel will load the initrd to
RAM in any case.

> whereas I would like to keep my romfs in flash.

Then use a flash filesystem.

> maybe I misunderstand and misuse completly the initrd... Help and hints
> welcome...

Have a look at the MTD layer. You have to enable MTD support  in  the
Linux kernel. Then you can define partitions on your flash memory and
create  block  devices  on  these. And on these block devices you can
uses filesystems - whichever you like.


But all of this is actually completely unrelated to U-Boot  and  thus
off topic here.


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
"What if" is a trademark of Hewlett Packard, so stop using it in your
sentences without permission, or risk being sued.

[U-Boot-Users] ROMFS & Uboot.

[Callebaut Benoit]

Hi,
If you have enough FLASH why do you want to use initrd. Make you ROMFS, build 
a kernel that supports it with the good flash parameters (start,length,CFI or 
not,...) set as root filesystem the flash device (/dev/mtdblock0 ) and go on. 
It works (It tested with CRAMFS which is a Compressed ROM file system 
uncompressing in RAM).

Do it the easy way.

Benoit Callebaut

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[U-Boot-Users] ROMFS & Uboot.

[Christophe.LINDHEIMER at fr.thalesgroup.com]

Hi.

> 
> 
> Hi,
> If you have enough FLASH why do you want to use initrd. 

In fact, it seems it is a stupid idea to use initrd :-) ( Linux newbie idea
... )

> Make you ROMFS, build 
> a kernel that supports it with the good flash parameters 
> (start,length,CFI or 
> not,...) set as root filesystem the flash device 
> (/dev/mtdblock0 ) and go on. 
> It works (It tested with CRAMFS which is a Compressed ROM file system 
> uncompressing in RAM).
> 

Ok. Thanks.

> Do it the easy way.
> 
> Benoit Callebaut
> 

[U-Boot-Users] ROMFS & Uboot.

[Christophe.LINDHEIMER at fr.thalesgroup.com]

Hi.

> > 
> > Well, my problem is that I am really short of ram.
> 
> Easy to fix: add more RAM. RAM is very cheap these days.

Harder to fix : explain hardware people that they shouldnt care about
current consumption and area of the card :-)

> 
> > So I would like to have my filesystem in flash and keep it in flash.
> > 
> > So I would like to have my root filesytem in flash ( possible ?? ).
> > romfs seems to be a way to do it.
> 
> Of course this is possible. And there  are  many  ways  to  implement
> this: romfs, cramfs, jffs2, ...
> 
> > It think the way to do it it to declare my romfs as initrd 
> ( maybe I am
> > wrong because initrd is init ram disk and it means that it 
> MUST be a RW
> > filesystem in RAM ??? )
> 
> Right. An initrd is a RAM disk. And a RAM disk is in RAM by 
> definition.
> 
> > After reading sources of U Boot it seems that if I put a 
> second parameter at
> > bootm, it is going to copy the initrd into RAM ( right ? ).
> 
> Not really. Current versions of U-Boot allow to avoid the extra  copy
> of  the  ramdisk  image. But the LInux kernel will load the initrd to
> RAM in any case.
> 
> > whereas I would like to keep my romfs in flash.
> 
> Then use a flash filesystem.
> 
> > maybe I misunderstand and misuse completly the initrd... 
> Help and hints
> > welcome...
> 
> Have a look at the MTD layer. You have to enable MTD support  in  the
> Linux kernel. Then you can define partitions on your flash memory and
> create  block  devices  on  these. And on these block devices you can
> uses filesystems - whichever you like.
> 
> 
> But all of this is actually completely unrelated to U-Boot  and  thus
> off topic here.
> 

Ok . thanks for help. I gonna look this.

Regards

Chris

[U-Boot-Users] ROMFS & Uboot.

[Murray Jensen]

On Tue, 10 Jun 2003 17:00:18 +0200, Christophe.LINDHEIMER at fr.thalesgroup.com writes:
>So I would like to have my root filesytem in flash ( possible ?? ).
>romfs seems to be a way to do it.

Check out Squashfs - the thing I like about it is that it supports all the
usual linux modes (file type, permission, etc.) and owner, group, etc. I am
in the process of converting to it now so I can't say how well it all works,
but it looks promising. More info at ... http://squashfs.sourceforge.net/
Cheers!
								Murray...
-- 
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