Have you guys considered a combination of a read-only rootfs (in squashfs or romfs) and a read-write jffs2 overlay using mini_fo, unionfs or some other overlay method? OpenWrt does this, and they do *all* the booting from the read-only part with a tmpfs overlay, and then swap the tmpfs and jffs2 overlay after the jffs2 has been mounted in the background. Fast boot, single jffs2, no change to packaging. -- Rod (top-posting from Treo650 - sorry to those it offends)
-----Original Message----- From: Andy Green <[EMAIL PROTECTED]> Date: Friday, Jan 11, 2008 10:23 pm Subject: Re: Fwd: Hello -- NAND/NOR Flash design for GTA02 To: Miles Hsieh <[EMAIL PROTECTED]> CC: Willie <[EMAIL PROTECTED]>, [email protected], Jim Huang <[EMAIL PROTECTED]>, =?UTF-8?B?IidNSUxFU19IU0lFSCAo6Kyd5Luy5YexKSci?= <[EMAIL PROTECTED]>, nod <[EMAIL PROTECTED]>, "Neng-Yu Tu \(Tony Tu\)" <[EMAIL PROTECTED]> -----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA1 > >Somebody in the thread at some point said: > Hi, Werner, Willie, Nod: > > production information now: > > device nand0 <neo1973-nand>, # parts = 6 > #: name size offset mask_flags > 0: u-boot 0x00040000 0x00000000 0 > 1: u-boot_env 0x00040000 0x00040000 0 > 2: kernel 0x00800000 0x00080000 0 > 3: splash 0x000a0000 0x00880000 0 > 4: factory 0x00040000 0x00920000 0 > 5: rootfs 0x076a0000 0x00960000 0 > >Okay by me, but one thing... there is a 20s target now for boot time. We have >to decide what to do to get ourselves much closer to this (I >don't think we will reach it) because we are far away from it right now. > >One of the choices that we may do is to cut rootfs into two, because the >amount of time spent mounting is proportional only to the partition >size. We can create a 50MB "early boot" partition we can mount to get started >with the initscripts, and mount the remaining 200MB in the >background at a different mountpoint. This will reduce the effective initial >JFFS2 mount time to 20% of what it is now. > >Werner is looking at trying to find a different way to optimize the mount >time, we said that early next week we will finalize the decision on the >partition set we will use, but I would propose we cut the rootfs in two as >described if Werner didn't have luck in speeding it up by a considerable >amount. Of course even if he speeds it up by 5% that is really good either >way. > >If we go that way, we need to consider the impact on packaging paths. Probably >we should leave all the packages to point where they are, and have /usr and so >on in the "early boot" partition. Then other packages should place stuff in >something like /opt or /usr/local which is mounted or mounted --bind to the >second, larger partition. > >- -Andy >-----BEGIN PGP SIGNATURE----- >Version: GnuPG v1.4.7 (GNU/Linux) >Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org > >iD8DBQFHh1imOjLpvpq7dMoRAqRlAJ9+HhyzIHTlRjihqVICi1guUcG9JgCfR2y3 >2m69KPvwUed1+pJivYOQ1fM= >=V+Mt >-----END PGP SIGNATURE----- > >
