On Mon, 2013-10-28 at 16:04 +0100, Pali Rohár wrote:

On Monday 28 October 2013 15:56:55 Johannes Berg wrote:

quoted

On Mon, 2013-10-28 at 09:46 -0500, Dan Williams wrote:

quoted

If the device doesn't actually *have* a permanent MAC
address, then it shouldn't be returning one via ethtool,
and should return an error for ETHTOOL_GPERMADDR.

There's currently no provision for that, but I agree it would
be better to do so.

johannes

So what to do with devices which has MAC address stored in some 
obscure place and there is userspace binary which can read it?

I think that there should be some way to tell kernel that *this* 
is the permanent address and it should use it.

This is reason why I proposed patch which adding sysfs entry for 
setting permanent address from userspace in wl1251 driver.

Ok, so the N900's MAC is stored in the "cal partition", which is a
region of flash exposed to the OS as /dev/mtd1.  That also stores the
regulatory domain.  Typically userspace binaries are used to pull out
this and other data (see
https://dev.openwrt.org/browser/packages/utils/calvaria/files/src/calvaria.c ) which is then used to initialize the device.

Any idea what kernel driver is used to expose the CAL partition
as /dev/mtd1?  If it's nothing special maybe a small EEPROM-style driver
could be written to read the relevant areas (and since they don't ever
change, don't need to worry about something else writing at the same
time).

Dan