On Thursday 12 May 2016 19:08:30 Mario_Limonciello@xxxxxxxx wrote:
> > > We do mirror the information in ACPI under the system bus:
> > >
> > > Scope (_SB)
> > > {
> > > Name (AMAC, Buffer (0x17)
> > > {
> > > "_AUXMAC_#847BEB5992D2#"
> > > })
> > > }
> > >
> > > I don't know how to properly access this from the kernel side. I noticed
> > that most drivers that reference ACPI nodes refer to devices, not something
> > hanging off the system bus.
> > > If you could advise the right way to go about that, I would appreciate it.
> >
> > So there are two ways how to read that MAC address. One is via SMM and
> > one via ACPI.
>
> Yes, this isn't a general statement for read only static information, but in this case it is true.
>
> > You can also read ACPI buffer (name is probably \_SB.AMAC) with ACPI
> > functions in kernel. Ask ACPI people, for correct API. I'm sure this is possible
> > also without creating new ACPI driver...
>
> Thanks will do.
I think that acpi_get_handle() and acpi_evaluate_object() methods are
those which you want to use.
> > > If I can access that, maybe it's better to do this directly as a patch to the
> > Ethernet driver in question (r8152).
> > > That's actually how it's handled on the OS side for Windows too from what I
> > understand.
> > > We have some FW bit set in them to indicate they're Dell Realtek products
> > (don't have this detail yet).
> > > When they see that bit they look for that ACPI buffer and use it to set the
> > MAC address the OS sees.
> >
> > Maybe it should be better to chose same way as Windows drivers? Better
> > ask on netdev mailing list and ping maintainers of that ethernet driver what
> > they think about it.
> >
> > For me it sounds like a better solution (patching that ethernet driver) as
> > exporting some non-standard sysfs node from kernel with MAC address and
> > then using another tool which send that MAC address back to kernel.
> >
>
> Great, thank you for your feedback. I'll wander down that rabbit hole.
Ok, CC me next discussion.
--
Pali Rohár
pali.rohar@xxxxxxxxx
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