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

From: Joakim Tjernlund <joakim.tjernlund@transmode.se>
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 08:41:08 +0100	[thread overview]
Message-ID: <OFE141BEC6.2AD09552-ONC1257663.002976D8-C1257663.002A37E3@transmode.se> (raw)
In-Reply-To: <COL117-W39489EB6F20294AE9A03B8EEB20@phx.gbl>

>
> 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
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.
 - impl. a better crc32(use the one from linux)
 - Don't scan more than you have to, that is, ls/read /some/file
   should only scan and keep records to do the ls/read of that
   particular file.

There were some patches floating around quite some time ago to improve
scanning but I don't think they made it into the u-boot repo.

    Jocke