Re: [PATCH 3/5] pci: switch pci_conf_{read/write} to use pci_sbdf_t

From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
	Julien Grall <julien.grall@arm.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Brian Woods <brian.woods@amd.com>
Subject: Re: [PATCH 3/5] pci: switch pci_conf_{read/write} to use pci_sbdf_t
Date: Tue, 28 May 2019 12:05:29 +0200	[thread overview]
Message-ID: <20190528100529.apc7rlpdzvgr3vzf@Air-de-Roger> (raw)
In-Reply-To: <5CECF68A0200007800232E9B@prv1-mh.provo.novell.com>

On Tue, May 28, 2019 at 02:51:22AM -0600, Jan Beulich wrote:
> >>> On 27.05.19 at 18:44, <roger.pau@citrix.com> wrote:
> > On Fri, May 24, 2019 at 04:01:23AM -0600, Jan Beulich wrote:
> >> >>> On 10.05.19 at 18:10, <roger.pau@citrix.com> wrote:
> >> > --- a/xen/include/xen/pci.h
> >> > +++ b/xen/include/xen/pci.h
> >> > @@ -58,6 +58,11 @@ typedef union {
> >> >      };
> >> >  } pci_sbdf_t;
> >> >  
> >> > +#define PCI_SBDF_T(s, b, d, f) \
> >> > +    ((pci_sbdf_t) { .seg = (s), .bus = (b), .dev = (d), .func = (f) })
> >> 
> >> I'd prefer if the _T suffix could be omitted. Afaics there's no use of the
> >> existing PCI_SBDF() anywhere in the tree, so this should be fine. For
> >> the 2nd macro below I can't easily tell whether the few existing used
> >> have all disappeared by now, but it seems likely.
> > 
> > I can see about dropping the _T suffix, but I think there's likely
> > some overlap between the introduction of PCI_SBDF_T and the last user
> > of the current PCI_SBDF helpers, so maybe it's fine to use the _T
> > suffix at first and have one final patch that removes it?
> 
> That would be an option if it can't be done in one go, sure.
> 
> >> Also I'm afraid initializers of this kind will break the build with old gcc.
> > 
> > I thought we dropped support for such old versions of gcc, is that not
> > the case?
> 
> No yet, as per ./README.

Right, so then I guess the only solution would be to use something
like:

#define PCI_SBDF_T(s, b, d, f) \
    ((pci_sbdf_t) { .sbdf = PCI_SBDF(s,b,d,f) })

And similarly for the other initializers. I guess then you would be
fine with using the _T suffix for those helpers and keeping the
current ones as-is?

Thanks, Roger.

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