Re: [Hx4700-port] Custom kernel and root on SD or CF cards
Andrey Bondarenko
If you would use journal file system you would get one part of it
(journal) always wrote down on each write operation. That would
dramatically cut lifetime of your card because physically journal
would be located on a limited set of memory sells. That is why ext3
and Raiser are not recommended on any flash media.
2006/8/9, Alexei Chamine <chami...@mail.ru>:
>
>
> Some pitfalls when trying to build a kernel for hx4700 to boot with
> HaRET and root on SD and CF cards:
>
> About SD: Maybe it was because of my SD-card (Transcend 1G) - but when I
> installed debian on it - sometimes my linux freezes on heavy write
> operations such as 'apt-get upgrade' or so. I mounted it either with and
> without 'sync' option. Don't know where was a bug - but with CF-card
> (Transcend 2G) my debian write there normally. (kernel was 2.6.16-hh2)
>
> Card partitioning and formatting: card can contain only one linux
> partition - HaRET and kernel can be stored in PDA's Windows folders, but
> only if you have WM5. Someone told me that ext2 is faster for flash cards -
> can be a reasons for that?
>
> Kernel compilation:
> Better (and sometimes is only way to boot i think) to compile your own.
> Here i noticed one problem - if your gzipped kernel image will be larger
> that something like 1.3 megs - HaRET will not boot it - only said 'UART
> initialized' in serial line then freezes. Maybe someone knows what it can
> be???
> When compiling with initrd usage: I noticed that someone (including
> myself) after boot completition can't free memory that was eaten by initrd
> (unmount /initrd folder in instance). Second (in case of SD-card) - kernel
> can't find /dev/mmcblk0p[X] device: solutions are different (?): first - i
> hear that this device must be created with mknod in /dev of your initrd
> image and second - you must use another device - /dev/mmc/partX/blkY instead
> (e.g. /dev/mmc/part0/blk1, also must create it with mknod in your initrd
> image).
> When compiling without initrd: first trouble - you must build-in some
> modules that will be needed to boot - like reiserfs, ext2, pcmcia-ide,
> ata/atapi, etc... but kernel must not be large (see above). Second - kernel
> will not recognize your CF/SD card that will result in VFS: unable to mount
> on unknown-block error message. One solution (from Matt Reimer about
> unrecognized CF-card) is to check your CF-card manufacturer/product id's:
> ---
> Another idea: see if your card is listed in drivers/ide/legacy/ide-cs.c in
> the ide_ids table. I just had a problem on hx4700 where my CF card wasn't
> listed and so wasn't automatically recognized. I booted linux, inserted the
> CF card and did this:
> root_at_h2200:/sys/devices/platform/pxa2xx-pcmcia.0/0.0#
> cat manf_id
> 0x000a
> root_at_h2200:/sys/devices/platform/pxa2xx-pcmcia.0/0.0#
> cat card_id
> 0x0000
> root_at_h2200:/sys/devices/platform/pxa2xx-pcmcia.0/0.0#
> cat func_id
> 0x04
> root_at_h2200:/sys/devices/platform/pxa2xx-pcmcia.0/0.0#
> cat prod_id1
> TRANSCEND
> root_at_h2200:/sys/devices/platform/pxa2xx-pcmcia.0/0.0#
> cat prod_id2
> TS1GCF80
> Then I took manf_id and card_id and added a line to ide_ids:
> PCMCIA_DEVICE_MANF_CARD(0x000a, 0x0000), /* Transcend */
> Now my CF card is detected at boot.
> ---
> In my case - I was also needed to add rootdelay=5 (can be more or less)
> option to boot parameters.
>
> OK, now my kernel is booting with root on CF without initrd normally ...
> but that questions still bother me:
> 1. Is Ext2 is really faster than Ext3 or ReiserFS in case of CF/SD
> cards? And why if so.
> 2. Really HaRET can freeze when kernel size is big?
> 3. Do anyone who use familiar from SD-card have freezes when heavily
> writing something on it? (Although i am using debian on my hx4700 - i think
> it depends on kernel drivers of somewhere there).
>
> /// Chamine
>
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>
>
--
WBR,
Andrey "Shaman007" Bondarenko
http://mobilelinux.ru
http://mobilelinux.ru/wiki
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