Re: Can i access the barebox env from linux

[Michel Stam <michel@reverze.net>]

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Hey Alex,

The current version? That is a library, quite ugly actually.
LD_PRELOAD=/lib/LIBRARY /command/to/execute

The preload overrides the libc calls to open/read/write files.
The command can then access the environment sector, read only. If the 
environment contains a /bin/init, then the file will be available from 
/bin/init if the library is preloaded. Memory footprint is around 
10kbyte RAM, or something like that. Its probably only usable for root, 
as it requires read access to the block device, something you wouldn't 
want to give all users.

As a kernel module I would make it a proper filesystem so you can do 
something like mount /dev/blockdev /path -t bbfs.
That kernel driver will probably be a long-term project, though.

Cheers,

Michel
On 03/26/2014 12:58 PM, Alexander Aring wrote:
> On Wed, Mar 26, 2014 at 12:53:03PM +0100, Michel Stam wrote:
>> In case anyone is interested; for a barebox x86 project I wrote a library
>> that overrides fopen/fclose/open/close/etc a while back, which allows read
>> access to the environment sector if properly configured. I managed to get it
>> working on arm/mips with mtdblock as well.
>>
>> In the near future I'd like to write a kernel driver to read the filesystem
>> properly, this was more of an experiment.
>>
> How does it work? As a kernel module, as registered filesystem under
> /proc/filesystems ?
>
> With fuse as userspace filesystem?
>
> Or like the inotify solution?
>
> - Alex



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