Re: firmware discussion

[Joe Talbott <josepht@xxxxxxxxxx>]

On Tue, May 04, 2010 at 12:13:50PM +0300, Aggelos Economopoulos wrote:
> Johannes Hofmann wrote:
> > Matthew Dillon <dillon@apollo.backplane.com> wrote:
> >>    Well, the DFly kernel has some very easy-to-use file access functions
> >>    ala fp_open() and friends (see kern_checkpoint.c for a use case), so
> >>    accessing the firmware file directly is easy enough.
> > 
> > I thought about writing a generic firmware module using the new
> > FreeBSD API which reads firmware files from a certain directory
> > using fp_open().
> > However, it seems that available firmware images need to be announced
> > with firmware_register() to make them available, so I would need some
> > sort of opendir() in kernel to scan the firmware directory and
> > register the available files with firmware_register().
> 
> ... and also to monitor the directory for changes :)
> 
> > Alternatively we could adjust subr_firmware.c to trigger a file read
> > attempt in case the requested image has not yet been registered.
> 
> Yah, in firmware_get(), it already handles the case where the module
> containing the firmware isn't loaded yet. You can add the directory
> search in loadimage() or better yet in a separate function (i.e. have
> loadimage() call load_image_module() and load_image_blob()). This makes
> much more sense IMO.
> 

I think this is a good idea with the one caveat that I don't fully
understand the security implications of arbitrarily loading blobs into
kernel memory.  I was thinking of something along the lines of
/etc/firmware.conf that maps a short name as used by the FreeBSD API
to a filename in /etc/firmware.

Johannes, feel free to implement this if you'd like.  I am pretty busy
with real life at the moment.

Thanks,
Joe