* [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-18 15:50 ` Andre Przywara
0 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-18 15:50 UTC (permalink / raw)
To: will.deacon; +Cc: Michael Ellerman, Matt Evans, kvm, kvm-ppc, kvmarm
Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
for LD.
Allow people to override the compiler name by specifying it explicitly
on the command line or via the environment.
Beside calling a certain compiler binary this allows to pass in
options to the compiler, which lets us get rid of the PowerPC
overrides in the Makefile. Possible uses:
$ make CC="gcc -m64" LD="ld -melf64ppc"
(build kvmtool on a PowerPC toolchain defaulting to 32-bit)
$ make CC="gcc -m32" LD="ld -melf_i386"
(build a 32-bit binary on a multilib-enabled x86-64 compiler)
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
Makefile | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 6110b8e..888bee5 100644
--- a/Makefile
+++ b/Makefile
@@ -14,9 +14,13 @@ export E Q
include config/utilities.mak
include config/feature-tests.mak
-CC := $(CROSS_COMPILE)gcc
+ifeq ($(origin CC), default)
+ CC := $(CROSS_COMPILE)gcc
+endif
CFLAGS :-LD := $(CROSS_COMPILE)ld
+ifeq ($(origin LD), default)
+ LD := $(CROSS_COMPILE)ld
+endif
LDFLAGS :
FIND := find
@@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
OBJS += powerpc/spapr_pci.o
OBJS += powerpc/xics.o
ARCH_INCLUDE := powerpc/include
- CFLAGS += -m64
- LDFLAGS += -m elf64ppc
ARCH_WANT_LIBFDT := y
endif
--
2.3.5
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-18 15:50 ` Andre Przywara
0 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-18 15:50 UTC (permalink / raw)
To: will.deacon; +Cc: Michael Ellerman, Matt Evans, kvm, kvm-ppc, kvmarm
Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
for LD.
Allow people to override the compiler name by specifying it explicitly
on the command line or via the environment.
Beside calling a certain compiler binary this allows to pass in
options to the compiler, which lets us get rid of the PowerPC
overrides in the Makefile. Possible uses:
$ make CC="gcc -m64" LD="ld -melf64ppc"
(build kvmtool on a PowerPC toolchain defaulting to 32-bit)
$ make CC="gcc -m32" LD="ld -melf_i386"
(build a 32-bit binary on a multilib-enabled x86-64 compiler)
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
Makefile | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 6110b8e..888bee5 100644
--- a/Makefile
+++ b/Makefile
@@ -14,9 +14,13 @@ export E Q
include config/utilities.mak
include config/feature-tests.mak
-CC := $(CROSS_COMPILE)gcc
+ifeq ($(origin CC), default)
+ CC := $(CROSS_COMPILE)gcc
+endif
CFLAGS :=
-LD := $(CROSS_COMPILE)ld
+ifeq ($(origin LD), default)
+ LD := $(CROSS_COMPILE)ld
+endif
LDFLAGS :=
FIND := find
@@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
OBJS += powerpc/spapr_pci.o
OBJS += powerpc/xics.o
ARCH_INCLUDE := powerpc/include
- CFLAGS += -m64
- LDFLAGS += -m elf64ppc
ARCH_WANT_LIBFDT := y
endif
--
2.3.5
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
2015-06-18 15:50 ` Andre Przywara
@ 2015-06-19 1:14 ` Michael Ellerman
-1 siblings, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2015-06-19 1:14 UTC (permalink / raw)
To: Andre Przywara; +Cc: will.deacon, Matt Evans, kvm, kvm-ppc, kvmarm
On Thu, 2015-06-18 at 16:50 +0100, Andre Przywara wrote:
> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
> for LD.
> Allow people to override the compiler name by specifying it explicitly
> on the command line or via the environment.
> Beside calling a certain compiler binary this allows to pass in
> options to the compiler, which lets us get rid of the PowerPC
> overrides in the Makefile. Possible uses:
> $ make CC="gcc -m64" LD="ld -melf64ppc"
> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
> $ make CC="gcc -m32" LD="ld -melf_i386"
> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
I'm not a big fan of that.
Your examples are all about overriding CFLAGS and LDFLAGS, not CC and LD. So
if anything you should be allowing that. Adding flags to CC and LD is asking
for trouble.
cheers
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-19 1:14 ` Michael Ellerman
0 siblings, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2015-06-19 1:14 UTC (permalink / raw)
To: Andre Przywara; +Cc: will.deacon, Matt Evans, kvm, kvm-ppc, kvmarm
On Thu, 2015-06-18 at 16:50 +0100, Andre Przywara wrote:
> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
> for LD.
> Allow people to override the compiler name by specifying it explicitly
> on the command line or via the environment.
> Beside calling a certain compiler binary this allows to pass in
> options to the compiler, which lets us get rid of the PowerPC
> overrides in the Makefile. Possible uses:
> $ make CC="gcc -m64" LD="ld -melf64ppc"
> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
> $ make CC="gcc -m32" LD="ld -melf_i386"
> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
I'm not a big fan of that.
Your examples are all about overriding CFLAGS and LDFLAGS, not CC and LD. So
if anything you should be allowing that. Adding flags to CC and LD is asking
for trouble.
cheers
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
2015-06-19 1:14 ` Michael Ellerman
@ 2015-06-19 10:00 ` Andre Przywara
-1 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-19 10:00 UTC (permalink / raw)
To: Michael Ellerman, Will Deacon
Cc: Matt Evans, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
kvmarm@lists.cs.columbia.edu
Hi Michael,
On 19/06/15 02:14, Michael Ellerman wrote:
> On Thu, 2015-06-18 at 16:50 +0100, Andre Przywara wrote:
>> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
>> for LD.
>> Allow people to override the compiler name by specifying it explicitly
>> on the command line or via the environment.
>> Beside calling a certain compiler binary this allows to pass in
>> options to the compiler, which lets us get rid of the PowerPC
>> overrides in the Makefile. Possible uses:
>> $ make CC="gcc -m64" LD="ld -melf64ppc"
>> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
>> $ make CC="gcc -m32" LD="ld -melf_i386"
>> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>
>
> I'm not a big fan of that.
>
> Your examples are all about overriding CFLAGS and LDFLAGS, not CC and LD. So
> if anything you should be allowing that. Adding flags to CC and LD is asking
> for trouble.
Will just disabled overriding CFLAGS and LDFLAGS, I think because
kvmtool inherited some C nastiness from the kernel, which does not
compile with random flags set (CFLAGS=-std=gnu99 was the one the broke it).
Maybe we should revisit that, either fix the code to be more robust to
comply with various standards or document that you should not have
CFLAGS set. Then allow overriding CFLAGS again.
But I thought that overriding CC is common practise - if you want to
select a different compiler, that is. Using a different bitness seems a
lot like a different compiler to me, same with different endianness.
I think I saw quite some examples on the web about using CC="gcc -m32".
I agree that abusing CC to pass optimization options to the compiler is
not good, but for kvmtool's Makefile I don't see how adding flags to CC
would hurt.
Cheers,
Andre.
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-19 10:00 ` Andre Przywara
0 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-19 10:00 UTC (permalink / raw)
To: Michael Ellerman, Will Deacon
Cc: Matt Evans, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
kvmarm@lists.cs.columbia.edu
Hi Michael,
On 19/06/15 02:14, Michael Ellerman wrote:
> On Thu, 2015-06-18 at 16:50 +0100, Andre Przywara wrote:
>> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
>> for LD.
>> Allow people to override the compiler name by specifying it explicitly
>> on the command line or via the environment.
>> Beside calling a certain compiler binary this allows to pass in
>> options to the compiler, which lets us get rid of the PowerPC
>> overrides in the Makefile. Possible uses:
>> $ make CC="gcc -m64" LD="ld -melf64ppc"
>> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
>> $ make CC="gcc -m32" LD="ld -melf_i386"
>> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>
>
> I'm not a big fan of that.
>
> Your examples are all about overriding CFLAGS and LDFLAGS, not CC and LD. So
> if anything you should be allowing that. Adding flags to CC and LD is asking
> for trouble.
Will just disabled overriding CFLAGS and LDFLAGS, I think because
kvmtool inherited some C nastiness from the kernel, which does not
compile with random flags set (CFLAGS=-std=gnu99 was the one the broke it).
Maybe we should revisit that, either fix the code to be more robust to
comply with various standards or document that you should not have
CFLAGS set. Then allow overriding CFLAGS again.
But I thought that overriding CC is common practise - if you want to
select a different compiler, that is. Using a different bitness seems a
lot like a different compiler to me, same with different endianness.
I think I saw quite some examples on the web about using CC="gcc -m32".
I agree that abusing CC to pass optimization options to the compiler is
not good, but for kvmtool's Makefile I don't see how adding flags to CC
would hurt.
Cheers,
Andre.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
2015-06-18 15:50 ` Andre Przywara
@ 2015-06-19 9:59 ` Paolo Bonzini
-1 siblings, 0 replies; 10+ messages in thread
From: Paolo Bonzini @ 2015-06-19 9:59 UTC (permalink / raw)
To: Andre Przywara, will.deacon; +Cc: kvm-ppc, Michael Ellerman, kvm, kvmarm
On 18/06/2015 17:50, Andre Przywara wrote:
> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
> for LD.
> Allow people to override the compiler name by specifying it explicitly
> on the command line or via the environment.
> Beside calling a certain compiler binary this allows to pass in
> options to the compiler, which lets us get rid of the PowerPC
> overrides in the Makefile. Possible uses:
> $ make CC="gcc -m64" LD="ld -melf64ppc"
> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
> $ make CC="gcc -m32" LD="ld -melf_i386"
> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> Makefile | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 6110b8e..888bee5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -14,9 +14,13 @@ export E Q
> include config/utilities.mak
> include config/feature-tests.mak
>
> -CC := $(CROSS_COMPILE)gcc
> +ifeq ($(origin CC), default)
> + CC := $(CROSS_COMPILE)gcc
> +endif
> CFLAGS :> -LD := $(CROSS_COMPILE)ld
> +ifeq ($(origin LD), default)
> + LD := $(CROSS_COMPILE)ld
> +endif
I know zero about the kvmtool build system, but that ought not to be
necessary. The make manual says:
"If a variable has been set with a command argument (*note Overriding
Variables: Overriding.), then ordinary assignments in the makefile are
ignored."
Paolo
> LDFLAGS :>
> FIND := find
> @@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
> OBJS += powerpc/spapr_pci.o
> OBJS += powerpc/xics.o
> ARCH_INCLUDE := powerpc/include
> - CFLAGS += -m64
> - LDFLAGS += -m elf64ppc
>
> ARCH_WANT_LIBFDT := y
> endif
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-19 9:59 ` Paolo Bonzini
0 siblings, 0 replies; 10+ messages in thread
From: Paolo Bonzini @ 2015-06-19 9:59 UTC (permalink / raw)
To: Andre Przywara, will.deacon; +Cc: kvm-ppc, Michael Ellerman, kvm, kvmarm
On 18/06/2015 17:50, Andre Przywara wrote:
> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
> for LD.
> Allow people to override the compiler name by specifying it explicitly
> on the command line or via the environment.
> Beside calling a certain compiler binary this allows to pass in
> options to the compiler, which lets us get rid of the PowerPC
> overrides in the Makefile. Possible uses:
> $ make CC="gcc -m64" LD="ld -melf64ppc"
> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
> $ make CC="gcc -m32" LD="ld -melf_i386"
> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> Makefile | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 6110b8e..888bee5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -14,9 +14,13 @@ export E Q
> include config/utilities.mak
> include config/feature-tests.mak
>
> -CC := $(CROSS_COMPILE)gcc
> +ifeq ($(origin CC), default)
> + CC := $(CROSS_COMPILE)gcc
> +endif
> CFLAGS :=
> -LD := $(CROSS_COMPILE)ld
> +ifeq ($(origin LD), default)
> + LD := $(CROSS_COMPILE)ld
> +endif
I know zero about the kvmtool build system, but that ought not to be
necessary. The make manual says:
"If a variable has been set with a command argument (*note Overriding
Variables: Overriding.), then ordinary assignments in the makefile are
ignored."
Paolo
> LDFLAGS :=
>
> FIND := find
> @@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
> OBJS += powerpc/spapr_pci.o
> OBJS += powerpc/xics.o
> ARCH_INCLUDE := powerpc/include
> - CFLAGS += -m64
> - LDFLAGS += -m elf64ppc
>
> ARCH_WANT_LIBFDT := y
> endif
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
2015-06-19 9:59 ` Paolo Bonzini
@ 2015-06-19 10:23 ` Andre Przywara
-1 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-19 10:23 UTC (permalink / raw)
To: Paolo Bonzini, Will Deacon
Cc: kvm-ppc@vger.kernel.org, Michael Ellerman, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu
Hi Paolo,
On 19/06/15 10:59, Paolo Bonzini wrote:
>
>
> On 18/06/2015 17:50, Andre Przywara wrote:
>> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
>> for LD.
>> Allow people to override the compiler name by specifying it explicitly
>> on the command line or via the environment.
>> Beside calling a certain compiler binary this allows to pass in
>> options to the compiler, which lets us get rid of the PowerPC
>> overrides in the Makefile. Possible uses:
>> $ make CC="gcc -m64" LD="ld -melf64ppc"
>> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
>> $ make CC="gcc -m32" LD="ld -melf_i386"
>> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> Makefile | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 6110b8e..888bee5 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -14,9 +14,13 @@ export E Q
>> include config/utilities.mak
>> include config/feature-tests.mak
>>
>> -CC := $(CROSS_COMPILE)gcc
>> +ifeq ($(origin CC), default)
>> + CC := $(CROSS_COMPILE)gcc
>> +endif
>> CFLAGS :>> -LD := $(CROSS_COMPILE)ld
>> +ifeq ($(origin LD), default)
>> + LD := $(CROSS_COMPILE)ld
>> +endif
>
> I know zero about the kvmtool build system,
Well, it inherits a lot from the kernel ;-)
> but that ought not to be
> necessary. The make manual says:
>
> "If a variable has been set with a command argument (*note Overriding
> Variables: Overriding.), then ordinary assignments in the makefile are
> ignored."
Right, there was this nasty difference between "CC=gcc make" and
"make CC=gcc". So I agree that the latter works even without that patch.
Guess I was only looking at the environment here.
Paolo, thanks for pointing out!
Will, please ignore this patch then.
Cheers,
Andre.
>
> Paolo
>
>> LDFLAGS :>>
>> FIND := find
>> @@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
>> OBJS += powerpc/spapr_pci.o
>> OBJS += powerpc/xics.o
>> ARCH_INCLUDE := powerpc/include
>> - CFLAGS += -m64
>> - LDFLAGS += -m elf64ppc
>>
>> ARCH_WANT_LIBFDT := y
>> endif
>>
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] kvmtool: Makefile: allow overriding CC and LD
@ 2015-06-19 10:23 ` Andre Przywara
0 siblings, 0 replies; 10+ messages in thread
From: Andre Przywara @ 2015-06-19 10:23 UTC (permalink / raw)
To: Paolo Bonzini, Will Deacon
Cc: kvm-ppc@vger.kernel.org, Michael Ellerman, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu
Hi Paolo,
On 19/06/15 10:59, Paolo Bonzini wrote:
>
>
> On 18/06/2015 17:50, Andre Przywara wrote:
>> Currently we set CC unconditionally to ${CROSS_COMPILE}gcc, the same
>> for LD.
>> Allow people to override the compiler name by specifying it explicitly
>> on the command line or via the environment.
>> Beside calling a certain compiler binary this allows to pass in
>> options to the compiler, which lets us get rid of the PowerPC
>> overrides in the Makefile. Possible uses:
>> $ make CC="gcc -m64" LD="ld -melf64ppc"
>> (build kvmtool on a PowerPC toolchain defaulting to 32-bit)
>> $ make CC="gcc -m32" LD="ld -melf_i386"
>> (build a 32-bit binary on a multilib-enabled x86-64 compiler)
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> Makefile | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 6110b8e..888bee5 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -14,9 +14,13 @@ export E Q
>> include config/utilities.mak
>> include config/feature-tests.mak
>>
>> -CC := $(CROSS_COMPILE)gcc
>> +ifeq ($(origin CC), default)
>> + CC := $(CROSS_COMPILE)gcc
>> +endif
>> CFLAGS :=
>> -LD := $(CROSS_COMPILE)ld
>> +ifeq ($(origin LD), default)
>> + LD := $(CROSS_COMPILE)ld
>> +endif
>
> I know zero about the kvmtool build system,
Well, it inherits a lot from the kernel ;-)
> but that ought not to be
> necessary. The make manual says:
>
> "If a variable has been set with a command argument (*note Overriding
> Variables: Overriding.), then ordinary assignments in the makefile are
> ignored."
Right, there was this nasty difference between "CC=gcc make" and
"make CC=gcc". So I agree that the latter works even without that patch.
Guess I was only looking at the environment here.
Paolo, thanks for pointing out!
Will, please ignore this patch then.
Cheers,
Andre.
>
> Paolo
>
>> LDFLAGS :=
>>
>> FIND := find
>> @@ -148,8 +152,6 @@ ifeq ($(ARCH), powerpc)
>> OBJS += powerpc/spapr_pci.o
>> OBJS += powerpc/xics.o
>> ARCH_INCLUDE := powerpc/include
>> - CFLAGS += -m64
>> - LDFLAGS += -m elf64ppc
>>
>> ARCH_WANT_LIBFDT := y
>> endif
>>
>
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2015-06-19 10:23 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-06-18 15:50 [PATCH] kvmtool: Makefile: allow overriding CC and LD Andre Przywara
2015-06-18 15:50 ` Andre Przywara
2015-06-19 1:14 ` Michael Ellerman
2015-06-19 1:14 ` Michael Ellerman
2015-06-19 10:00 ` Andre Przywara
2015-06-19 10:00 ` Andre Przywara
2015-06-19 9:59 ` Paolo Bonzini
2015-06-19 9:59 ` Paolo Bonzini
2015-06-19 10:23 ` Andre Przywara
2015-06-19 10:23 ` Andre Przywara
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