Date: Thu, 2 Apr 2015 23:59:21 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, 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
Subject: Re: [PATCH v2] pci: export class IDs from pci_ids.h
Message-ID: <20150402215921.GA3942@kroah.com>
References: <1427714755-16873-1-git-send-email-mst@redhat.com>
 <20150402205347.GA10892@google.com>
 <20150402232804-mutt-send-email-mst@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150402232804-mutt-send-email-mst@redhat.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2262
Lines: 48

On Thu, Apr 02, 2015 at 11:28:19PM +0200, Michael S. Tsirkin wrote:
> 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.

So you want us to create yet-a-third-location for these values?  Both
libpci and libudev are on all systems.  And it's not a run-time
dependancy you are talking about here, but a build-time one, which is
quite different.  Having a build-time dependancy on packages that ship
with all Linux distributions seems acceptable to me.

thanks,

greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/