How to quickly write cleanmarkers to jffs2 partitions?

How to quickly write cleanmarkers to jffs2 partitions?

[David Jander]

Hi,

I was wondering if there is a trick or common technique I am ignoring to make 
this more efficient:

This is for a 2.4 kernel based system.
In production we use either u-boot or a NFS mounted linux system to erase 
flash and write jffs2 partitions to it. The jffs2 images are small (not 
padded to full partition size to save programming time), but the partitions 
are rather big (12 Mbyte in one case). Problem is that when booting for the 
first time, one has to wait several minutes (during which the system is more 
or less useless and busy) to get all cleanmarkers written to flash by the 
jffs2 gc thread. This huge delay is rather unacceptable for production, so we 
are looking for a work-around.

One option would be to make jffs2 images that are padded to full partition 
size, but that also isn't very efficient, considering the image is only about 
100k in beginning and the partition is 12 Mbyte in size. That would take a 
lot of time programming flash (less time than having the jffs2 driver fix 
this nevertheless).

Another option is making a little program that writes cleanmarkers in every 
eraseblock starting from the first completely empty one in a partition before 
mounting that partition for the very first time after flashing.

Since this seems to me like a common situation, I'd like to know if anybody 
knows about a better solution, or if anybody has already dealt with this 
before.

Greetings,

-- 
David Jander
Protonic Holland.
tel.: +31 (0) 229 212928
fax.: +31 (0) 229 210930
Factorij 36 / 1689 AL Zwaag

Re: How to quickly write cleanmarkers to jffs2 partitions?

[Jaap-Jan Boor]

Hi David,

I indeed did write a small program that only writes the cleanmarkers
in all flash blocks used for jffs2. We assume (and check) all flash  
sectors
are erased already.

Jaap-Jan

On 2-mrt-2006, at 17:06, David Jander wrote:

>
> Hi,
>
> I was wondering if there is a trick or common technique I am  
> ignoring to make
> this more efficient:
>
> This is for a 2.4 kernel based system.
> In production we use either u-boot or a NFS mounted linux system to  
> erase
> flash and write jffs2 partitions to it. The jffs2 images are small  
> (not
> padded to full partition size to save programming time), but the  
> partitions
> are rather big (12 Mbyte in one case). Problem is that when booting  
> for the
> first time, one has to wait several minutes (during which the  
> system is more
> or less useless and busy) to get all cleanmarkers written to flash  
> by the
> jffs2 gc thread. This huge delay is rather unacceptable for  
> production, so we
> are looking for a work-around.
>
> One option would be to make jffs2 images that are padded to full  
> partition
> size, but that also isn't very efficient, considering the image is  
> only about
> 100k in beginning and the partition is 12 Mbyte in size. That would  
> take a
> lot of time programming flash (less time than having the jffs2  
> driver fix
> this nevertheless).
>
> Another option is making a little program that writes cleanmarkers  
> in every
> eraseblock starting from the first completely empty one in a  
> partition before
> mounting that partition for the very first time after flashing.
>
> Since this seems to me like a common situation, I'd like to know if  
> anybody
> knows about a better solution, or if anybody has already dealt with  
> this
> before.
>
> Greetings,
>
> -- 
> David Jander
> Protonic Holland.
> tel.: +31 (0) 229 212928
> fax.: +31 (0) 229 210930
> Factorij 36 / 1689 AL Zwaag
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>
> -- 
> This message has been scanned for viruses and is believed to be clean
>

____
J.G.J. Boor                       Anton Philipsweg 1
Software Engineer                 1223 KZ Hilversum
AimSys bv                         tel. +31 35 689 1941
Postbus 2194, 1200 CD Hilversum   jjboor at aimsys dot nl

Re: How to quickly write cleanmarkers to jffs2 partitions?

[Mathieu Deschamps]

On Thursday 02 March 2006 17:06, David Jander wrote:
> Hi,
>
> I was wondering if there is a trick or common technique I am ignoring to
> make this more efficient:
>
> This is for a 2.4 kernel based system.
> In production we use either u-boot or a NFS mounted linux system to erase
> flash and write jffs2 partitions to it. The jffs2 images are small (not
> padded to full partition size to save programming time), but the partitions
> are rather big (12 Mbyte in one case). Problem is that when booting for the
> first time, one has to wait several minutes (during which the system is
> more or less useless and busy) to get all cleanmarkers written to flash by
> the jffs2 gc thread. This huge delay is rather unacceptable for production,
> so we are looking for a work-around.
>
> One option would be to make jffs2 images that are padded to full partition
> size, but that also isn't very efficient, considering the image is only
> about 100k in beginning and the partition is 12 Mbyte in size. That would
> take a lot of time programming flash (less time than having the jffs2
> driver fix this nevertheless).
>
> Another option is making a little program that writes cleanmarkers in every
> eraseblock starting from the first completely empty one in a partition
> before mounting that partition for the very first time after flashing.
>
> Since this seems to me like a common situation, I'd like to know if anybody
> knows about a better solution, or if anybody has already dealt with this
> before.
>
> Greetings,


Hi,

"When preparing a flash partition for JFFS2, it is recommended to put 
cleanmarkers to the erased blocks.
This might be done my means of "-j" option of the "flash_eraseall" MTD 
utility. Otherwise, JFFS2 will re-erase the blocks
which contain all 0xFF and have no cleanmarker. This is an unneeded wasting of 
time."

Source : http://www.linux-mtd.infradead.org/faq/jffs2.html

does this may be relevant ?



Best Regards,


Mathieu Deschamps.

Re: How to quickly write cleanmarkers to jffs2 partitions?

[Jaap-Jan Boor]

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On Fri, 2006-03-03 at 10:08 +0100, Mathieu Deschamps wrote:

> Hi,
> 
> "When preparing a flash partition for JFFS2, it is recommended to put 
> cleanmarkers to the erased blocks.
> This might be done my means of "-j" option of the "flash_eraseall" MTD 
> utility. Otherwise, JFFS2 will re-erase the blocks
> which contain all 0xFF and have no cleanmarker. This is an unneeded wasting of 
> time."
> 
> Source : http://www.linux-mtd.infradead.org/faq/jffs2.html
> 
> does this may be relevant ?

This is correct, however flash_eraseall does also (as it's
name suggests, erase all flash blocks, which takes
some time on NOR flash. If you 'know' the flash is erased,
it's not needed.
I used flash_eraseall to write the cleanmarkers, but without
erasing blocks (and called that utility cleanmark)

Jaap-Jan

> 
> 
> 
> Best Regards,
> 
> 
> Mathieu Deschamps.
> 
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 

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Re: How to quickly write cleanmarkers to jffs2 partitions?

[David Jander]

On Monday 06 March 2006 13:21, Jaap-Jan Boor wrote:
> On Fri, 2006-03-03 at 10:08 +0100, Mathieu Deschamps wrote:
> > Hi,
> >
> > "When preparing a flash partition for JFFS2, it is recommended to put
> > cleanmarkers to the erased blocks.
> > This might be done my means of "-j" option of the "flash_eraseall" MTD
> > utility. Otherwise, JFFS2 will re-erase the blocks
> > which contain all 0xFF and have no cleanmarker. This is an unneeded
> > wasting of time."
> >
> > Source : http://www.linux-mtd.infradead.org/faq/jffs2.html
> >
> > does this may be relevant ?
>
> This is correct, however flash_eraseall does also (as it's
> name suggests, erase all flash blocks, which takes
> some time on NOR flash. If you 'know' the flash is erased,
> it's not needed.
> I used flash_eraseall to write the cleanmarkers, but without
> erasing blocks (and called that utility cleanmark)

Thanks to all for the suggestions.
Is "cleanmark" an open-source tool? Would you share it?

Greetings,

-- 
David Jander

Re: How to quickly write cleanmarkers to jffs2 partitions?

[Jaap-Jan Boor]

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On Wed, 2006-03-08 at 09:38 +0100, David Jander wrote:

> 
> Thanks to all for the suggestions.
> Is "cleanmark" an open-source tool? 

well, I think so, as it's a minimal modified flash_eraseall.c from mtd

> Would you share it?

sure, a gzipped version is attached. Put it in the mtd/util directory
and add it to the Makefile there (to TARGETS) and:

cleanmark: crc32.o cleanmark.o
        $(CC) $(LDFLAGS) -o $@ $^


best regards,

Jaap-Jan

> 
> Greetings,
> 
> -- 
> David Jander
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 

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