[OpenWrt-Devel] Some standard partition name for extra user data?
blogic at openwrt.org
Sun Dec 7 10:22:33 EST 2014
On 07/12/2014 16:18, Rafał Miłecki wrote:
> On 7 December 2014 at 16:11, John Crispin <blogic at openwrt.org>
>> On 07/12/2014 16:05, Hauke Mehrtens wrote:
>>> On 12/07/2014 01:30 AM, Rafał Miłecki wrote:
>>>> I've bcm53xx device which has two usable flashes: 1) SPI
>>>> serial flash for CFE + firmware + NVRAM 2) NAND flash for
>>>> extra data
>>>> Because of general design of OpenWrt firmware my image
>>>> contains two partitions: kernel and rootfs (SquashFS).
>>>> Automatically rootfs_data (JFFS2) is created right after
>>>> I wanted to make space on NAND flash also usable for OpenWrt.
>>>> Do you have any advice on that?
>>>> 1) The coolest idea would be to use some LVM solution, but I
>>>> don't think we have anything like this ready in OpenWrt. Or
>>>> do we? AFAIK UBI itself can't work as LVM (can't use blocks
>>>> from several MTD partitions)?
>>>> 2) So I was thinking about simply registering that NAND
>>>> partition with some name we could make common across OpenWrt
>>>> targets. Something like "extra_data" or whatever you prefer.
>>>> User would need to mount it and use a proper directory for
>>>> storing his data. Is there anything like this in any other
>>>> Yet another solution could be to ignore this few MiB space on
>>>> serial flash and simply use NAND for rootfs_data. But this
>>>> would: 1) Waste some minor space on SPI serial flash 2) Would
>>>> require hacking partitioner to don't create rootfs_data 3)
>>>> Hacking UBI a bit I guess
>>> I assume these device are loading the kernel from serial flash
>>> by default.
>>> Have you looked at extroot:
>>> http://wiki.openwrt.org/doc/howto/extroot This is used to place
>>> the root file system on an external storage.
>> extroot is the wrong pattern for 2 flash setups.
>>>> 1) Waste some minor space on SPI serial flash
>> how big is spi / nand
> SPI serial flash is 16 MiB NAND is 128 MiB
>>>> 2) Would require hacking partitioner to don't create
>> huh ? ubifs ?
> I have to store "rootfs" on SPI serial due to CFE flashing method.
> Since "rootfs" is there, OpenWrt will create "rootfs_data" right
> after it. So with a partition "rootfs_data" on NAND I'd end up with
> two "rootfs_data" partitions. Since this is a device with SPI
> serial flash, I don't use UBI there (it's squashfs + jffs2 right
which board is this ? does the orig fw use the nand for data only ?
>>>> 3) Hacking UBI a bit I guess
>> sound like a wrong assumption no idea why you think ubi wont work
>> on your flash
> I guess I was thinking about a way to create UBI partition on NAND
> flash, create UBI volume + format it. Since this is a separated
> flash, I couldn't use ubinize for that.
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