[PATCH] [RFC] user-cr: Eliminate SUBARCH from Makefile

[PATCH] [RFC] user-cr: Eliminate SUBARCH from Makefile

[Matt Helsley]

[ Depends on recent series of non-RFC Makefile patches ]

SUBARCH is gross. We shouldn't need to detect the arch to compile to
using uname. It's bad practice because we could be using a cross compiler,
or someone may (gag) autoconfiscate this tree. If we must select a true
subarch, we should just let builders set -mXX in CFLAGS.

This patch tries to build all of the clone_*.[cSs] files. Any builds
that fail are quietly ignored and don't get used. One that succeeds
gets hardlinked to clone.a and subsequently linked into libeclone.a

This makes SUBARCH unnecessary.

Only tested on x86-32 so far. This also doesn't properly add clone.a
to libclone.a for some reason.

Signed-off-by: Matt Helsley <matthltc-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 Makefile |   55 ++++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/Makefile b/Makefile
index 60ddccd..03acea7 100644
--- a/Makefile
+++ b/Makefile
@@ -5,9 +5,6 @@ CKPT_HEADERS = include/linux/checkpoint.h \
 		include/linux/checkpoint_hdr.h \
 		include/asm/checkpoint_hdr.h
 
-# detect architecture (for eclone)
-SUBARCH = $(patsubst i%86,x86_32,$(shell uname -m))
-
 # compile with debug ?
 DEBUG = -DCHECKPOINT_DEBUG
 
@@ -42,24 +39,44 @@ $(LIB_ECLONE):
 # restart needs to be thread-safe
 restart: CFLAGS += -D__REENTRANT -pthread
 
+# Set CFLAGS to -m32 or -m64 to select a non-default subarch.
+# Hence we don't need the commented out CFLAGS-setting rules
+# immediately below.
+
+# clone_ppc.o: CFLAGS += -m32
+clone_ppc_.o: ASFLAGS += -m32
+# clone_ppc64.o: CFLAGS += -m64
+clone_ppc64_.o: ASFLAGS += -m64
+
+# powerpc clone.a requires two object files
+clone_ppc.a: clone_ppc_.o clone_ppc.o
+	$(AR) ruv $@ $^
+
+clone_ppc64.a: clone_ppc64_.o clone_ppc64.o
+	$(AR) ruv $@ $^
+
+# The remaining arch's clone.a all share the following rule
+%.a: %.o
+	$(AR) ruv $@ $^
+
+# Unlike normal rule dependencies, we want to link libeclone with the
+# object files that build successfully and ignore the rest. Normally
+# we do this by testing which will build and then setting a variable
+# for the dependency to use. Here we just depend on all the real source
+# files and hardlink the result of a successful build.
+clone.a: $(shell echo clone_*.[cSs])
+	@$(MAKE) -s clone_x86_32.a && ln clone_x86_32.a clone.a || /bin/true
+	@$(MAKE) -s clone_x86_64.a && ln clone_x86_64.a clone.a || /bin/true
+	@$(MAKE) -s clone_ppc.a && ln clone_ppc.a clone.a || /bin/true
+	@$(MAKE) -s clone_ppc64.a && ln clone_ppc64.o clone.a || /bin/true
+	@$(MAKE) -s clone_s390x.a && ln clone_s390x.o clone.a || /bin/true
+
 # eclone() is architecture specific
-ifneq ($(SUBARCH),)
-$(ECLONE_PROGS): $(LIB_ECLONE) 
+# TODO why doesn't clone.a link properly into libeclone.a??
+$(ECLONE_PROGS): $(LIB_ECLONE) clone.a
 $(ECLONE_PROGS): CFLAGS += -DARCH_HAS_ECLONE
-$(LIB_ECLONE): clone_$(SUBARCH).o genstack.o
-endif
-
-# on powerpc, need also assembly file
-ifeq ($(SUBARCH),ppc)
-CFLAGS += -m32
-ASFLAGS += -m32
-$(LIB_ECLONE): clone_$(SUBARCH)_.o
-endif
-ifeq ($(SUBARCH),ppc64)
-CFLAGS += -m64
-ASFLAGS += -m64
-$(LIB_ECLONE): clone_$(SUBARCH)_.o
-endif
+$(LIB_ECLONE): clone.a genstack.o
+
 
 # ckptinfo dependencies
 ckptinfo: ckptinfo_types.o
-- 
1.6.3.3

Re: [PATCH] [RFC] user-cr: Eliminate SUBARCH from Makefile

[Nathan Lynch]

On Fri, 2010-02-26 at 12:37 -0800, Matt Helsley wrote:
> [ Depends on recent series of non-RFC Makefile patches ]
> 
> SUBARCH is gross. We shouldn't need to detect the arch to compile to
> using uname. It's bad practice because we could be using a cross compiler,
> or someone may (gag) autoconfiscate this tree. If we must select a true
> subarch, we should just let builders set -mXX in CFLAGS.
> 
> This patch tries to build all of the clone_*.[cSs] files. Any builds
> that fail are quietly ignored and don't get used. One that succeeds
> gets hardlinked to clone.a and subsequently linked into libeclone.a

Hmm, I think detecting the architecture via uname is fine as long as the
user is able to override it (make SUBARCH=foo).

I don't think trying to compile all of clone_* is going to be a good
practice.  For one thing, gcc -m64 on powerpc happily accepted the
32-bit clone wrapper the last time I tried it, hence the #error
directives in clone_ppc*.S.

[PATCH user-cr] User can override SUBARCH for cross-compilation

[Oren Laadan]

Detecting the architecture via uname is fine as long as the user is
able to override it (make SUBARCH=foo).

Signed-of-by: Oren Laadan <orenl-eQaUEPhvms7ENvBUuze7eA@public.gmane.org>
---
 Makefile |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index 60ddccd..64b5f73 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,11 @@
+# *DOCUMENTATION*
+#
+# List of environment variables that may be set by caller:
+#  KERNELSRC	- path of kernel sources (def: ../linux)
+#  SUBARCH	- sub-architecture (def: extract with 'uname')
+#  PREFIX	- prefix path for installation (def: /usr/local)
+#
+
 KERNELSRC ?= ../linux
 
 CKPT_INCLUDE = -I./include
@@ -6,7 +14,7 @@ CKPT_HEADERS = include/linux/checkpoint.h \
 		include/asm/checkpoint_hdr.h
 
 # detect architecture (for eclone)
-SUBARCH = $(patsubst i%86,x86_32,$(shell uname -m))
+SUBARCH ?= $(patsubst i%86,x86_32,$(shell uname -m))
 
 # compile with debug ?
 DEBUG = -DCHECKPOINT_DEBUG
-- 
1.6.3.3

Re: [PATCH user-cr] User can override SUBARCH for cross-compilation

[Nathan Lynch]

Hey Oren,

On Mon, 2010-03-01 at 10:50 -0500, Oren Laadan wrote:
> Detecting the architecture via uname is fine as long as the user is
> able to override it (make SUBARCH=foo).
> 
> Signed-of-by: Oren Laadan <orenl-eQaUEPhvms7ENvBUuze7eA@public.gmane.org>
> ---
>  Makefile |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 60ddccd..64b5f73 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1,3 +1,11 @@
> +# *DOCUMENTATION*
> +#
> +# List of environment variables that may be set by caller:
> +#  KERNELSRC	- path of kernel sources (def: ../linux)
> +#  SUBARCH	- sub-architecture (def: extract with 'uname')
> +#  PREFIX	- prefix path for installation (def: /usr/local)
> +#
> +
>  KERNELSRC ?= ../linux
>  
>  CKPT_INCLUDE = -I./include
> @@ -6,7 +14,7 @@ CKPT_HEADERS = include/linux/checkpoint.h \
>  		include/asm/checkpoint_hdr.h
>  
>  # detect architecture (for eclone)
> -SUBARCH = $(patsubst i%86,x86_32,$(shell uname -m))
> +SUBARCH ?= $(patsubst i%86,x86_32,$(shell uname -m))

I didn't mean to imply that the user-cr Makefile didn't already honor
the user's SUBARCH setting on the command line.  That is, "make
SUBARCH=ppc" works fine already, since command line assignment of
variables overrides assignment within the Makefile.

Re: [PATCH user-cr] User can override SUBARCH for cross-compilation

[Oren Laadan]

Nathan Lynch wrote:
> Hey Oren,
> 
> On Mon, 2010-03-01 at 10:50 -0500, Oren Laadan wrote:
>> Detecting the architecture via uname is fine as long as the user is
>> able to override it (make SUBARCH=foo).
>>
>> Signed-of-by: Oren Laadan <orenl-eQaUEPhvms7ENvBUuze7eA@public.gmane.org>
>> ---
>>  Makefile |   10 +++++++++-
>>  1 files changed, 9 insertions(+), 1 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 60ddccd..64b5f73 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -1,3 +1,11 @@
>> +# *DOCUMENTATION*
>> +#
>> +# List of environment variables that may be set by caller:
>> +#  KERNELSRC	- path of kernel sources (def: ../linux)
>> +#  SUBARCH	- sub-architecture (def: extract with 'uname')
>> +#  PREFIX	- prefix path for installation (def: /usr/local)
>> +#
>> +
>>  KERNELSRC ?= ../linux
>>  
>>  CKPT_INCLUDE = -I./include
>> @@ -6,7 +14,7 @@ CKPT_HEADERS = include/linux/checkpoint.h \
>>  		include/asm/checkpoint_hdr.h
>>  
>>  # detect architecture (for eclone)
>> -SUBARCH = $(patsubst i%86,x86_32,$(shell uname -m))
>> +SUBARCH ?= $(patsubst i%86,x86_32,$(shell uname -m))
> 
> I didn't mean to imply that the user-cr Makefile didn't already honor
> the user's SUBARCH setting on the command line.  That is, "make
> SUBARCH=ppc" works fine already, since command line assignment of
> variables overrides assignment within the Makefile.
> 

Using "?=" allows a user to set SUBARCH as an environment variable
(and not have to repeatedly type it). Sinmple "=" does not pick up
a default value from the environment.

I'll fix the commit message to be more accurate.

Oren

Re: [PATCH user-cr] User can override SUBARCH for cross-compilation

[Nathan Lynch]

On Mon, 2010-03-01 at 14:05 -0500, Oren Laadan wrote:
> Using "?=" allows a user to set SUBARCH as an environment variable
> (and not have to repeatedly type it). Sinmple "=" does not pick up
> a default value from the environment.

That is true.


> I'll fix the commit message to be more accurate.

Thanks!