From: ken s. <ken...@gm...> - 2006-11-26 18:07:30
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On 11/25/06, M. Edward (Ed) Borasky <zn...@ce...> wrote: > Andrei Rylin wrote: > > Hi all, > > I just went thru setting a root filesystem on MMC, > > http://docwiki.gumstix.org/Root_filesystems did help > > a lot but there were a few things that was omitted > > or incorrect, so I just want to share an experience... > > First, the text should mention that > > gumstix-factory.script is not a text file, but > > an output of > > 'build_arm_nofpu/u-boot-1.1.4/tools/mkimage' > > Exact parameters I used were > > mkimage -A arm -O linux -T script -C none -a 0 -e 0 \ > > -n "whatever here" -d <infile> <outfile> > > Second, the script itself shall not include > > 'rdinit=/bin/sh' as part of bootargs as it's supposed > > to run /init in ramdisk.img, not /bin/sh > > Third, idea of loop-mounting ext2 (or whatever) image > > form vfat partition may be convenient for testing, > > but it's an extra layer and is totally unnecessary > > for a permanent setup. > > So I created 2 primary partitions on my MMC: > > small vfat that contains gumstix-factory.script, > > uImage and ramdisk.img, the rest went to ext3 > > Accordingly, uboot has to load images not from 'mmc 0' > > but from 'mmc 1'. Of course, I had to change a few > > lines here and there (/init, /etc/fstab). > > I also like to have 'errors=remount-ro' in /etc/fstab > > Works like a clock now ! > > > > > Thanks!! I've been working on this myself, paging through the scattered > documentation. I finally got something running the other day using the > files on the wiki, but I'm in the process of building my own, so this is > very timely. > > A general question -- what has been the experience with ext3 filesystems > on flash devices here? I've found on regular rotating disks, the > performance of ext3 on write-intensive applications is abysmal, because > of the journaling. I don't really trust it, so I've been sticking with ext2. > Figure 4: Disk performance for several different filesystems. Figure 5: Performance using none, one, two or three virtual disk indirection layers. on page 6 of this paper: http://arxiv.org/ftp/cs/papers/0508/0508063.pdf if you use ext2, you'll need to do clean shutdowns. ext3's journal will help with "just pull the plug" the choice of filesystem depends on the requirements for your application. --- ken |