[coreboot] Trac reminder: list of new ticket(s)

Eric W. Biederman ebiederm at xmission.com
Wed Jul 16 07:36:41 CEST 2008

Stefan Reinauer <stepan at coresystems.de> writes:

> Eric W. Biederman wrote:
>> coreboot tracker <svn at coreboot.org> writes:
>>> #110   Allow for per-device subsystem IDs
>> What is the proper procedure for saying per-device subsystem IDs is
>> a dumb idea.
>> The subsystem IDs roughly identify the PCB a component sits on.  So
>> unless you have multiple pluggable boards in a system there should
>> only be one subsystem vendor and one subsystem device id.
> Is this the official definition? Where does this originate from?

A Paraphrased version of the official definition.  It comes from
the PCI SIG as I recall.  I haven't rechecked this since I added
support years ago.

> In practice the subsystem vendor IDs are quite arbitrary and definitely not the
> same for all PCI devices per mainboard on any of the mainboards we have here. In
> fact, what I have seen quite often is that every PCI device has it's
> device/vendor ID set as subsystem IDs.

Which is probably a default, giving you no board information.
Quite likely a bug.  The subsystem vendor is not supposed to
be the ASIC vendor.

> The subsystem information is used by lspci to correctly identify some
> devices. 

Yes.  You need to know which board they are on, to identify them.

> Plus, more importantly, we use it in flashrom to identify
> mainboards. Using a unique device ID per board will require us to have two sets
> of information, one for legacy bios and one for coreboot.
That sounds weird.

> While using per-board subsystem ids sounds the right thing as per your
> reasoning, I vote to not enforce that behavior, but make it configurable.

I can understand overriding it for compatibility, or in other weird cases.
The default should still be global to the mainboard.


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