Re: linux-parisc compile failure in current git

[Helge Deller <deller@gmx.de>]

* Masahiro Yamada <masahiroy@kernel.org>:
> On Thu, Jun 10, 2021 at 4:04 PM Helge Deller <deller@gmx.de> wrote:
> >
> > Hi Masahiro,
> >
> > On 6/10/21 4:03 AM, Masahiro Yamada wrote:
> > > On Thu, Jun 10, 2021 at 7:50 AM Helge Deller <deller@gmx.de> wrote:
> > >>
> > >> On 6/1/21 12:21 PM, Meelis Roos wrote:
> > >>> Upstream Linux git fails to compile on gentoo hppa -  .config below.
> > >>> I have 2 gcc-s as always:
> > >>> $ gcc-config -l
> > >>>    [1] hppa2.0-unknown-linux-gnu-9.3.0
> > >>>    [2] hppa2.0-unknown-linux-gnu-10.2.0 *
> > >>>
> > >>>    [3] hppa64-unknown-linux-gnu-10.2.0 *
> > >>
> > >>
> > >> I see the same issue too, but only when compiling natively on a parisc machine.
> > >> Cross-compiling on a x86 box works nicely.
> > >>
> > >> First I thought it's a problem with setting the "cross_compiling" flag in ./Makefile.
> > >> But that's not sufficient.
> > >>
> > >> On a x86 machine (which builds fine) I get
> > >> SRCARCH=parisc SUBARCH=x86 UTS_MACHINE=parisc
> > >> The arch/parisc/kernel/asm-offsets.c file gets preprocessed via:
> > >> hppa64-linux-gnu-gcc
> > >>
> > >> On a native 32bit parisc machine I have:
> > >> SRCARCH=parisc SUBARCH=parisc UTS_MACHINE=parisc
> > >> Here the arch/parisc/kernel/asm-offsets.c file gets preprocessed via:
> > >> gcc
> > >> Instead here the native hppa64-linux-gnu-gcc (cross compiler) should have been used too, since
> > >> we build a 64-bit hppa kernel (CONFIG_64BIT is set).
> > >> Note, on hppa we don't have an "-m64" compiler flag as on x86.
> > >
> > > I see.
> > > hppa is not a bi-arch compiler, in other words,
> > > http- and hppa64- are separate compilers.
> >
> > Yes.
> >
> > >> Mashahiro, do you maybe have an idea what gets wrong here, or which
> > >> patch has changed the behaviour how the asm-offsets.c file gets preprocessed?
> > >
> > > Presumably, commit 23243c1ace9fb4eae2f75e0fe0ece8e3219fb4f3
> > >
> > > Prior to that commit, arch/parisc/Makefile was like this:
> > >
> > > ifneq ($(SUBARCH),$(UTS_MACHINE))
> > >          ifeq ($(CROSS_COMPILE),)
> > >                      ...
> > >
> > > Now I understand why arch/parisc/Makefile was written this way.
> > >
> > > Reverting the change in arch/parisc/Makefile will restore the original behavior.
> >
> > Sadly, reverting this change (23243c1ace9fb4eae2f75e0fe0ece8e3219fb4f3) does not
> > restore the original behavior.
> >
> > > But, please keep in mind that there is an issue remaining.
> > >
> > > Please see this code:
> > >
> > > ifdef CONFIG_64BIT
> > > UTS_MACHINE := parisc64
> > > CHECKFLAGS += -D__LP64__=1
> > > CC_ARCHES = hppa64
> > > LD_BFD := elf64-hppa-linux
> > > else # 32-bit
> > > CC_ARCHES = hppa hppa2.0 hppa1.1
> > > LD_BFD := elf32-hppa-linux
> > > endif
> > >
> > >
> > > UTS_MACHINE is determined by CONFIG_64BIT.
> > >
> > > CONFIG_64BIT is defined only after Kconfig is finished.
> > > When you are trying to configure the .config,
> > > CONFIG_64BIT is not defined yet.
> > > So UTS_MACHINE is always 'parisc'.
> >
> > Yes.
> > See above, but it worked when I had SUBARCH=x86 (when running my laptop).
> >
> >
> > > As you know, Kconfig files now have a bunch of 'cc-option' syntax
> > > to check the compiler capability in Kconfig time.
> > > Hence, you need to provide a proper compiler in Kconfig time too.
> > >
> > > When you build a 64-bit parisc kernel on a 32-bit parisc machine,
> >
> > Please note, that we don't have a 64-bit parisc userspace yet (just kernel).
> > This means, that all builds on parisc machines are 32bit and do a
> > cross-compilation to a parisc64 kernel if requested in the .config.
> >
> > > Kconfig is passed with CC=gcc since SUBARCH==UTS_MACHINE==parisc.
> > > After Kconfig, CROSS_COMPILE=hppa64-* is set,
> > > and the kernel is built by CC=hppa64-*-gcc.
> >
> > Right. That is the old behaviour. Based on the CONFIG_64BIT option
> > the hppa64 compiler is choosen for CROSS_COMPILE.
> >
> > > So, Kconfig evaluated a compiletely different compiler. This is pointless.
> >
> > Yes, probably.
> >
> >
> > > There are some options
> > >
> > > [option 1]
> > >    revert the parisc bit of 23243c1ace9fb4eae2f75e0fe0ece8e3219fb4f3
> > >    This will restore the functionality you may want, but
> > >    as I said above, Kconfig is doing pointless things.
> >
> > as mentioned above: Doesn't solve the issue.
> >
> > > [option 2]
> > >     Stop using cc-cross-prefix, and pass CROSS_COMPILE explicitly.
> > >     This is what many architectures including arm, arm64 do.
> > >     You need to explicitly pass CROSS_COMPILE=aarch64-linux-gnu- etc.
> > >     if you are cross-compiling arm64.
> >
> > Might be an option, but it's not as handy as simply choosing CONFIG_64BIT
> > and then things are done automatically.
> >
> > > [option 3]
> > >     Introduce ARCH=parisc64.
> > >
> > >     When you are building 64-bit kernel, you can pass ARCH=parisc64
> > >      A patch attached.  (but not tested much)
> >
> > Tried it, but doesn't work.
> > asm-offsets.c is still preprocessed with 32bit compiler (gcc, not hppa20-gcc).
> >
> > Thanks for your help so far!
> > If you like I'm happy to give you an account on a hppa64 machine to reproduce yourself.
> > I'll now try to bisect where it goes wrong. There must be something else before commit 23243c1ace9fb4eae2f75e0fe0ece8e3219fb4f3.
> >
> > Helge
>
>
> Sorry for my late reply.

Me too.... :-(

> Did git-bisect find something?

No. But I understood, that it's not a new problem.
It existed already before.

> If necessary, I will be happy to try it on the hppa64 machine.

Yes, please.
I'll send you login details in a private mail.
Attached is my last test patch (which is based on yours).

Helge

-----

diff --git a/Makefile b/Makefile
index ed669b2d705d..47a972f859f5 100644
--- a/Makefile
+++ b/Makefile
@@ -399,6 +399,11 @@ ifeq ($(ARCH),sparc64)
        SRCARCH := sparc
 endif

+# Additional ARCH settings for parisc
+ifeq ($(ARCH),parisc64)
+       SRCARCH := parisc
+endif
+
 export cross_compiling :=
 ifneq ($(SRCARCH),$(SUBARCH))
 cross_compiling := 1
diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile
index aed8ea29268b..ee5890a2f62d 100644
--- a/arch/parisc/Makefile
+++ b/arch/parisc/Makefile
@@ -25,18 +25,21 @@ CHECKFLAGS	+= -D__hppa__=1
 ifdef CONFIG_64BIT
 UTS_MACHINE	:= parisc64
 CHECKFLAGS	+= -D__LP64__=1
-CC_ARCHES	= hppa64
 LD_BFD		:= elf64-hppa-linux
 else # 32-bit
-CC_ARCHES	= hppa hppa2.0 hppa1.1
 LD_BFD		:= elf32-hppa-linux
 endif

 # select defconfig based on actual architecture
-ifeq ($(shell uname -m),parisc64)
+ifeq ($(ARCH),parisc64)
 	KBUILD_DEFCONFIG := generic-64bit_defconfig
+	CC_ARCHES := hppa64
+else ifdef CONFIG_64BIT
+	KBUILD_DEFCONFIG := generic-64bit_defconfig
+	CC_ARCHES := hppa64
 else
 	KBUILD_DEFCONFIG := generic-32bit_defconfig
+	CC_ARCHES := hppa hppa2.0 hppa1.1
 endif

 export LD_BFD
diff --git a/scripts/subarch.include b/scripts/subarch.include
index 650682821126..776849a3c500 100644
--- a/scripts/subarch.include
+++ b/scripts/subarch.include
@@ -7,7 +7,7 @@
 SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
 				  -e s/sun4u/sparc64/ \
 				  -e s/arm.*/arm/ -e s/sa110/arm/ \
-				  -e s/s390x/s390/ -e s/parisc64/parisc/ \
+				  -e s/s390x/s390/ \
 				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
 				  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \
 				  -e s/riscv.*/riscv/)