[U-Boot] Does uboot EBS(erase block summary) to reduce JFFS2 scaning time?

From: HeLei <leon.he@msn.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] Does uboot EBS(erase block summary) to reduce JFFS2	scaning time?
Date: Tue, 3 Nov 2009 17:26:44 +0800	[thread overview]
Message-ID: <COL117-W58FAA05805F981A1985CADEEB20@phx.gbl> (raw)
In-Reply-To: <OF4A9A2CF3.472AEF9C-ONC1257663.0032DDE2-C1257663.00334CA3@transmode.se>

Jocke, you are so kind.Thank you very much:)

> Subject: RE: [U-Boot] Does uboot EBS(erase block summary) to reduce JFFS2	scaning time?
> To: leon.he at msn.com
> CC: u-boot at lists.denx.de
> From: joakim.tjernlund at transmode.se
> Date: Tue, 3 Nov 2009 10:20:19 +0100
> 
> HeLei <leon.he@msn.com> wrote on 03/11/2009 09:21:04:
> >
> > Thank you, Jocke
> >
> > > Subject: Re: [U-Boot] Does uboot EBS(erase block summary) to reduce JFFS2
> > scaning time?
> > > To: leon.he at msn.com
> > > CC: u-boot at lists.denx.de
> > > From: joakim.tjernlund at transmode.se
> > > Date: Tue, 3 Nov 2009 08:41:08 +0100
> > >
> > >
> > > >
> > > > Hi, All
> > > >
> > > >
> > > >
> > > > Each time JFFS2 initialized, uboot need to scan the whole flash. This is
> > > > fairly time consuming.
> > > >
> > > >
> > > >
> > > > So EBS(erase block summary) is used to JFFS2 to reduce mounting time. And I
> > > > believe this can also be used to UBOOT to reduce booting time.
> > > >
> > > >
> > > >
> > > > Does UBOOT support this feature? or does any other solution in uboot to
> > > > reduce JFFS2 scaning time?
> > >
> > > Don't think EBS is going to buy you much. The main problem is that the
> >
> >    You mean even EBS is used in UBOOT, it will not give me much help. But it
> > seems there is great efficiency in jffs2 mounting, from some artical in
> > internet, such as:http://www.embedded-linux.co.uk/tutorial/jffs2-summary
> >
> > > scanning of JFFS2 in u-boot is inefficient. u-boot could take a
> > > hint from the kernel impl. of JFFS2 to reduce scanning. The biggest
> > > ones are:
> > > - do no scan the whole EB when it is empty.
> >    If we don't scan the block, how can we tell the EB is empty?
> >
> > > - impl. a better crc32(use the one from linux)
> 
> Attaching a very crude port of linux crc32. This boots a linux img
> for me and handles the environment crc as well. Feel free
> to clean it up and submit to u-boot.
> 
>      Jocke
> 
>      (See attached file: crc32-new.c)(See attached file: crc32defs.h)(See attached file: crc32table.h)

_________________________________________________________________
?????????????????msn?????
http://ditu.live.com/?form=TL&swm=1