linux-kernel - Re: [PATCH v5 RESEND 2/5] lib: move pci

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Date: Thu, 25 Jan 2024 12:31:07 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Philipp Stanner <pstanner@...hat.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
	Johannes Berg <johannes@...solutions.net>,
	Randy Dunlap <rdunlap@...radead.org>, NeilBrown <neilb@...e.de>,
	John Sanpe <sanpeqf@...il.com>,
	Kent Overstreet <kent.overstreet@...il.com>,
	Niklas Schnelle <schnelle@...ux.ibm.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Uladzislau Koshchanka <koshchanka@...il.com>,
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
	David Gow <davidgow@...gle.com>, Kees Cook <keescook@...omium.org>,
	Rae Moar <rmoar@...gle.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"wuqiang.matt" <wuqiang.matt@...edance.com>,
	Yury Norov <yury.norov@...il.com>, Jason Baron <jbaron@...mai.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Marco Elver <elver@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>, dakr@...hat.com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-arch@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v5 RESEND 2/5] lib: move pci_iomap.c to drivers/pci/

On Thu, Jan 25, 2024 at 03:54:51PM +0100, Philipp Stanner wrote:
> On Tue, 2024-01-23 at 14:20 -0600, Bjorn Helgaas wrote:
> > On Thu, Jan 11, 2024 at 09:55:37AM +0100, Philipp Stanner wrote:
> > > This file is guarded by an #ifdef CONFIG_PCI. It, consequently,
> > > does not
> > > belong to lib/ because it is not generic infrastructure.
> > > 
> > > Move the file to drivers/pci/ and implement the necessary changes
> > > to
> > > Makefiles and Kconfigs.
> > > ...
> > 
> > > --- a/drivers/pci/Kconfig
> > > +++ b/drivers/pci/Kconfig
> > > @@ -13,6 +13,11 @@ config FORCE_PCI
> > >         select HAVE_PCI
> > >         select PCI
> > >  
> > > +# select this to provide a generic PCI iomap,
> > > +# without PCI itself having to be defined
> > > +config GENERIC_PCI_IOMAP
> > > +       bool
> > 
> > > --- a/lib/pci_iomap.c
> > > +++ b/drivers/pci/iomap.c
> > > @@ -9,7 +9,6 @@
> > >  
> > >  #include <linux/export.h>
> > >  
> > > -#ifdef CONFIG_PCI
> > 
> > IIUC, in the case where CONFIG_GENERIC_PCI_IOMAP=y but CONFIG_PCI was
> > not set, pci_iomap.c was compiled but produced no code because the
> > entire file was wrapped with this #ifdef.
> > 
> > But after this patch, it looks like pci_iomap_range(),
> > pci_iomap_wc_range(), etc., *will* be compiled?
> > 
> > Is that what you intend, or did I miss something?
> 
> They *will* be compiled when BOTH, CONFIG_PCI and
> CONFIG_GENERIC_PCI_IOMAP have been set.

I was asking about CONFIG_GENERIC_PCI_IOMAP=y but CONFIG_PCI unset.

But the Makefile contains this:

  ifdef CONFIG_PCI
  obj-$(CONFIG_GENERIC_PCI_IOMAP) += iomap.o
  endif

So iomap.c will not be compiled when CONFIG_PCI is unset, which is
what I missed.

Bjorn