Re: Adding -N volume name to ubi utils

[Adrian Hunter <ext-adrian.hunter@nokia.com>]

Richard Titmuss wrote:
> I am trying to modify the ubi tools in mtd_utils to allow the ubi volume 
> name to be specified on the command line, the relevant commands are 
> ubinfo, ubirmvol and ubiupdatevol. The idea is that you could use any of 
> the following command arguments to specify a ubi volume:
> 
>    ubirmvol /dev/ubi0 -N rootfs    # ubi device node and volume name
>    ubirmvol /dev/ubi0 -n 1    # ubi device node and volume id
>    ubirmvol /dev/ubi0_1    # ubi volume node
> 
> Other than consistency the main feature this adds is support for using 
> -N to specify the volume by name to all the commands.
> 
> The problem is these commands need different information to work:
> - ubinfo loads information from the /sys file system, it's easy to 
> support for all the above command arguments.
> - ubirmvol needs a ubi device node and a volume id, how can this work if 
> a volume node is specified?
> - ubiupdatevol needs a ubi volume node, how can this work if a device 
> node is specified?
> 
> So my questions is how can the appropriate device node be generated by 
> these commands if it is not specified on the command line. It would be 
> possible to use something like:
>   sprintf(node, "/dev/ubi%d_%d", args.devn, args.vol_id);
> 
> However I don't think that hard coding the /dev path is an acceptable 
> solution, and assume that's why the -d (device number) argument was 
> deprecated. Does anyone have any suggestions on a better solution?

In principle, you should use udev rules to create device nodes that
are easy to work with e.g.

/dev/ubi/rootfs/vol
/dev/ubi/rootfs/dev

so then you can make a script say ubirmvolbyname

#!/bin/sh
ubirmvol /dev/ubi/$1/dev -N $1