Date: Thu, 2 Apr 2015 23:28:19 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        "David S. Miller" <davem@davemloft.net>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
        Alexei Starovoitov <ast@plumgrid.com>,
        stephen hemminger <stephen@networkplumber.org>,
        Masahiro Yamada <yamada.m@jp.panasonic.com>, linux-pci@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-api@vger.kernel.org,
        Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2] pci: export class IDs from pci_ids.h
Message-ID: <20150402232804-mutt-send-email-mst@redhat.com>
References: <1427714755-16873-1-git-send-email-mst@redhat.com>
 <20150402205347.GA10892@google.com>
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On Thu, Apr 02, 2015 at 03:53:47PM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 30, 2015 at 01:33:28PM +0200, Michael S. Tsirkin wrote:
> > The basic class ID macros in pci_ids.h are pretty useful for userspace
> > using the pci sysfs interface, and they aren't fundamentally different
> > from the constants in pci_regs.h - both are defined in the
> > pci spec.
> > 
> > At the moment userspace is forced to duplicate these macros
> > (e.g. QEMU does this, so do seabios, gpxe, and others), it is better to
> > expose them in /usr/include/linux/pci_ids.h so everyone can just include
> > this header.
> 
> I agree that it would be nice for applications to get these definitions
> from a single place, but I'm not sure that include/uapi/linux/pci_ids.h
> needs to be that place.
> 
> These constants are just copies of what's in the spec, and I don't think
> you're suggesting that the constants are necessary to use a kernel API.
> 
> I know the kernel does provide access to values via sysfs "class" files,
> but the kernel is just passing the values through from the hardware.
> That's analogous to reading the class with setpci, and I don't think it
> leads to a requirement that the kernel export all the information about how
> to interpret the class values.
> 
> I haven't looked at libpci or libudev, but it sounds like you think those
> are not good solutions.  Is that because they don't currently have this
> information?  People don't want to add dependencies on them?
> 
> Bjorn

People don't want to add dependencies on them.

-- 
MST
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