Re: [PATCH 1/1] pciutils: Add decode support for Data Object Exchange Extended Capability

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Jan 18, 2022 at 05:25:15PM +0000, Jonathan Cameron wrote:
> PCI Data Object Exchange [1] provides a mailbox interface used as the
> transport for various protocols defined by PCI-SIG and others. Make the
> limited information in config space available. Note the Read/Write
> Mailbox registers themselves are not currently parsed as the usefulness
> of accessing one dword of a protocol is probably limited.
> 
> In future, operating systems may provide means to safely query the
> supported protocols, but those have not yet been defined.
> 
> Example output:
> 
> Capabilities: [190 v1] Data Object Exchange
>                 DOECap: IntSup:+
>                         Interrupt Message Number: 001
>                 DOECtl: IntEn:-
>                 DOESta: Busy:- IntSta:- Error:- ObjectReady:-

Typical lspci output omits the ":" for each field, e.g., from your
test:

> +             DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
> +                     RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-

> [1] Data Object Exchange (DOE) ECN, approved 12 March 2020

DOE is included in the just-released PCIe r6.0 base spec, so we should
cite that (PCIe r6.0, sec 6.30, 7.9.24).

Bjorn