Re: [PATCH v2 5/5] ACPICA: Remove deprecated _LINUX definitions for ACPICA.

[Rafael J. Wysocki]

On 4/28/2014 6:10 AM, Zheng, Lv wrote:
> Hi, Rafael
>
> > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx]
> > Sent: Monday, April 28, 2014 5:39 AM
> >
> > On Wednesday, April 23, 2014 02:54:22 PM Lv Zheng wrote:
> > > There are _LINUX defined so that when Linux kernel is compiled using broken
> > > compilers that having not __linux__ defined can still include
> > > <acpi/platform/aclinux.h> from <acpi/platform/acenv.h>.
> > >
> > > This behavior is deprecated as all drivers/acpi/acpica files are compiled
> > > without including <linux/acpi.h>, thus without _LINUX defined.  As there is
> > > no issues encountered when we compile ACPICA code without _LINUX defined,
> > > it is OK to remove _LINUX from <linux/acpi.h> now.
> > >
> > > Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
> > > ---
> > >   include/linux/acpi.h |    4 ----
> > >   1 file changed, 4 deletions(-)
> > >
> > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > > index 7a8f2cd..9c559f7 100644
> > > --- a/include/linux/acpi.h
> > > +++ b/include/linux/acpi.h
> > > @@ -31,10 +31,6 @@
> > >
> > >   #ifdef	CONFIG_ACPI
> > >
> > > -#ifndef _LINUX
> > > -#define _LINUX
> > > -#endif
> > > -
> > >   #include <linux/list.h>
> > >   #include <linux/mod_devicetable.h>
> > What about <acpi/platform/acenv.h>?  Should it still check if _LINUX is defined
> > after this change?
> If you mean these lines:
>    #if defined(_LINUX) || defined(__linux__)
>    #include <acpi/platform/aclinux.h>
> After deleting "_LINUX" from <linux/acpi.h>, acenv.h still can include aclinux.h because of "__linux__".
> Actually all drivers/acpi/acpica source files are compiled without including <linux/acpi.h>, so "_LINUX" defined in this file is useless to Linux.
> We needn't delete "_LINUX" from acenv.h.
>
> "_LINUX" is only used in ACPICA makefiles, Linux never uses it:
>    https://github.com/acpica/acpica/blob/master/generate/unix/Makefile.config
> ACPICA can be compiled using the following make command:
>    make HOST=_LINUX
> I think this is the only usage of "_LINUX" for now.

Well, my point was: If we delete the definition of _LINUX, why don't we 
drop the symbol itself from everywhere along with it?

It definitely is not useful to refer to a symbol that's never defined, 
is it?

Rafael

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