Patchwork Thoughts around dtrace linking...

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Submitter Lee Essen
Date March 23, 2012, 2:11 p.m.
Message ID <BC75FF2D-E37D-4E2A-B079-D32AF0177233@nowonline.co.uk>
Download mbox | patch
Permalink /patch/148442/
State New
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Comments

Lee Essen - March 23, 2012, 2:11 p.m.
On 23 Mar 2012, at 08:08, Stefan Hajnoczi wrote:

> On Thu, Mar 22, 2012 at 05:00:53PM +0000, Lee Essen wrote:
>> On 22/03/2012 16:28, Stefan Hajnoczi wrote:
>>> On Wed, Mar 21, 2012 at 1:01 PM, Andreas Färber<afaerber@suse.de>  wrote:
>>>> Hi,
>>>> 
>>>> Am 21.03.2012 11:45, schrieb Lee Essen:
>>>>> I've been trying to find a sensible way to solve the Solaris/Illumos
>>>>> dtrace requirement to pass all the objs to the dtrace command so that
>>>>> the resultant object file contains all the symbols needed to properly
>>>>> link the relevant binary.
>>>>> 
> 
> If you're able to try out the dependency-based approach that would be a
> good starting point.  You may hit a point where it turns out to be too
> ugly or complicated - in that case, please post your progress and maybe
> someone can help find a way to structure it.  I'm not a make guru but I
> can try to give feedback on your patches.
> 
> Stefan
> 

Ok, here's an attempt … it works for me, but I'm not sure how it would work on a different dtrace platform so it will probably need some different guarding … but it shows what it will look like.

Lee.
Stefan Hajnoczi - March 26, 2012, 10:14 a.m.
On Fri, Mar 23, 2012 at 2:11 PM, Lee Essen <lee.essen@nowonline.co.uk> wrote:
>
> On 23 Mar 2012, at 08:08, Stefan Hajnoczi wrote:
>
>> On Thu, Mar 22, 2012 at 05:00:53PM +0000, Lee Essen wrote:
>>> On 22/03/2012 16:28, Stefan Hajnoczi wrote:
>>>> On Wed, Mar 21, 2012 at 1:01 PM, Andreas Färber<afaerber@suse.de>  wrote:
>>>>> Hi,
>>>>>
>>>>> Am 21.03.2012 11:45, schrieb Lee Essen:
>>>>>> I've been trying to find a sensible way to solve the Solaris/Illumos
>>>>>> dtrace requirement to pass all the objs to the dtrace command so that
>>>>>> the resultant object file contains all the symbols needed to properly
>>>>>> link the relevant binary.
>>>>>>
>>
>> If you're able to try out the dependency-based approach that would be a
>> good starting point.  You may hit a point where it turns out to be too
>> ugly or complicated - in that case, please post your progress and maybe
>> someone can help find a way to structure it.  I'm not a make guru but I
>> can try to give feedback on your patches.
>>
>> Stefan
>>
>
> Ok, here's an attempt … it works for me, but I'm not sure how it would work on a different dtrace platform so it will probably need some different guarding … but it shows what it will look like.

The code makes sense to me.  There's a feeling that there must be a
way to remove the duplication in this approach, but my make foo isn't
good enough to see how.

As you mentioned, we need a way to distinguish between Solaris DTrace,
which requires the global .o linking approach, and other
implementations.  You could use CONFIG_SOLARIS and CONFIG_TRACE_DTRACE
together to enable the global .o linking.

Stefan
Lee Essen - March 26, 2012, 3:28 p.m.
On 26/03/2012 11:14, Stefan Hajnoczi wrote:
> On Fri, Mar 23, 2012 at 2:11 PM, Lee Essen<lee.essen@nowonline.co.uk>  wrote:
>>
>> On 23 Mar 2012, at 08:08, Stefan Hajnoczi wrote:
>>
>>> On Thu, Mar 22, 2012 at 05:00:53PM +0000, Lee Essen wrote:
>>>> On 22/03/2012 16:28, Stefan Hajnoczi wrote:
>>>>> On Wed, Mar 21, 2012 at 1:01 PM, Andreas Färber<afaerber@suse.de>    wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Am 21.03.2012 11:45, schrieb Lee Essen:
>>>>>>> I've been trying to find a sensible way to solve the Solaris/Illumos
>>>>>>> dtrace requirement to pass all the objs to the dtrace command so that
>>>>>>> the resultant object file contains all the symbols needed to properly
>>>>>>> link the relevant binary.
>>>>>>>
>>>
>>> If you're able to try out the dependency-based approach that would be a
>>> good starting point.  You may hit a point where it turns out to be too
>>> ugly or complicated - in that case, please post your progress and maybe
>>> someone can help find a way to structure it.  I'm not a make guru but I
>>> can try to give feedback on your patches.
>>>
>>> Stefan
>>>
>>
>> Ok, here's an attempt … it works for me, but I'm not sure how it would work on a different dtrace platform so it will probably need some different guarding … but it shows what it will look like.
>
> The code makes sense to me.  There's a feeling that there must be a
> way to remove the duplication in this approach, but my make foo isn't
> good enough to see how.
>
> As you mentioned, we need a way to distinguish between Solaris DTrace,
> which requires the global .o linking approach, and other
> implementations.  You could use CONFIG_SOLARIS and CONFIG_TRACE_DTRACE
> together to enable the global .o linking.
>

So there is another way that's less duplicative on the non-target stuff. 
If you build all of the objects needed for ALL of the binaries, you 
could then build the dtrace object so that it was a superset, then link 
with that one in all of the final binary linking.

To be honest I think it's probably more confusing to do that, the 
previous approach is more duplicative but easier to follow.

Let me pull a full patch together and see what people think.

Lee.

Patch

diff --git a/Makefile b/Makefile
index 1bc3cb0..b300364 100644
--- a/Makefile
+++ b/Makefile
@@ -157,9 +157,28 @@  tools-obj-y = $(oslib-obj-y) $(trace-obj-y) qemu-tool.o qemu-timer.o \
        qemu-timer-common.o main-loop.o notify.o iohandler.o cutils.o async.o
 tools-obj-$(CONFIG_POSIX) += compatfd.o
 
-qemu-img$(EXESUF): qemu-img.o $(tools-obj-y) $(block-obj-y)
-qemu-nbd$(EXESUF): qemu-nbd.o $(tools-obj-y) $(block-obj-y)
-qemu-io$(EXESUF): qemu-io.o cmd.o $(tools-obj-y) $(block-obj-y)
+qemu-img-trace-objs=qemu-img.o $(tools-obj-y) $(block-obj-y)
+qemu-nbd-trace-objs=qemu-nbd.o $(tools-obj-y) $(block-obj-y)
+qemu-io-trace-objs=qemu-io.o cmd.o $(tools-obj-y) $(block-obj-y)
+qemu-img-all-objs=$(qemu-img-trace-objs)
+qemu-nbd-all-objs=$(qemu-nbd-trace-objs)
+qemu-io-all-objs=$(qemu-io-trace-objs)
+ifdef CONFIG_TRACE_DTRACE
+qemu-img-all-objs+=qemu-img.dtrace.o
+qemu-nbd-all-objs+=qemu-nbd.dtrace.o
+qemu-io-trace-objs+=qemu-img.dtrace.o
+endif
+
+qemu-img.dtrace.o: trace-dtrace.dtrace $(qemu-img-trace-objs)
+       $(call DTRACE,$@,trace-dtrace.dtrace,$(qemu-img-trace-objs))
+qemu-nbd.dtrace.o: trace-dtrace.dtrace $(qemu-nbd-trace-objs)
+       $(call DTRACE,$@,trace-dtrace.dtrace,$(qemu-nbd-trace-objs))
+qemu-io.dtrace.o: trace-dtrace.dtrace $(qemu-io-trace-objs)
+       $(call DTRACE,$@,trace-dtrace.dtrace,$(qemu-io-trace-objs))
+
+qemu-img$(EXESUF): $(qemu-img-all-objs)
+qemu-nbd$(EXESUF): $(qemu-nbd-all-objs)
+qemu-io$(EXESUF): $(qemu-io-all-objs)
 
 qemu-bridge-helper$(EXESUF): qemu-bridge-helper.o
 qemu-bridge-helper.o: $(GENERATED_HEADERS)
@@ -205,7 +224,17 @@  QGALIB_GEN=$(addprefix $(qapi-dir)/, qga-qapi-types.h qga-qapi-visit.h qga-qmp-c
 $(QGALIB_OBJ): $(QGALIB_GEN) $(GENERATED_HEADERS)
 $(qga-obj-y) qemu-ga.o: $(QGALIB_GEN) $(GENERATED_HEADERS)
 
-qemu-ga$(EXESUF): qemu-ga.o $(qga-obj-y) $(tools-obj-y) $(qapi-obj-y) $(qobject-obj-y) $(version-obj-y) $(QGALIB_OBJ)
+qemu-ga-trace-objs=qemu-ga.o $(qga-obj-y) $(tools-obj-y) $(qapi-obj-y) $(qobject-obj-y) $(version-obj-y) $(QGALIB_OBJ)
+qemu-ga-all-objs=$(qemu-ga-trace-objs)
+ifdef CONFIG_TRACE_DTRACE
+qemu-ga-all-objs+=qemu-ga.dtrace.o
+endif
+
+qemu-ga.dtrace.o: trace-dtrace.dtrace $(qemu-ga-trace-objs)
+       $(call DTRACE,$@,trace-dtrace.dtrace,$(qemu-ga-trace-objs))
+
+qemu-ga$(EXESUF): $(qemu-ga-all-objs)
+
 
 QEMULIBS=libhw32 libhw64 libuser libdis libdis-user
 
diff --git a/Makefile.target b/Makefile.target
index 63cf769..ed0d824 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -441,7 +441,17 @@  $(QEMU_PROGW): $(obj-y) $(obj-$(TARGET_BASE_ARCH)-y)
 $(QEMU_PROG): $(QEMU_PROGW)
        $(call quiet-command,$(OBJCOPY) --subsystem console $(QEMU_PROGW) $(QEMU_PROG),"  GEN   $(TARGET_DIR)$(QEMU_PROG)")
 else
-$(QEMU_PROG): $(obj-y) $(obj-$(TARGET_BASE_ARCH)-y)
+
+target-trace-objs=$(obj-y) $(obj-$(TARGET_BASE_ARCH)-y)
+target-all-objs=$(target-trace-objs)
+ifdef CONFIG_TRACE_DTRACE
+target-all-objs+=$(QEMU_PROG).dtrace.o
+endif
+
+$(QEMU_PROG).dtrace.o: ../trace-dtrace.dtrace $(target-trace-objs)
+       $(call DTRACE,$@,../trace-dtrace.dtrace,$(target-trace-objs))
+
+$(QEMU_PROG): $(target-all-objs)
        $(call LINK,$^)
 endif
 
diff --git a/rules.mak b/rules.mak
index 04a9198..31ad59c 100644
--- a/rules.mak
+++ b/rules.mak
@@ -33,6 +33,8 @@  endif
 
 LINK = $(call quiet-command,$(CC) $(QEMU_CFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ $(sort $(1)) $(LIBS),"  LINK  $(TARGET_DIR)$@")
 
+DTRACE = $(call quiet-command,dtrace $(CONFIG_DTRACE_FLAGS) -o $(1) -G -s $(2) $(3), "  GEN   $(TARGET_DIR)$(1)")
+
 %$(EXESUF): %.o
        $(call LINK,$^)