Re: [Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Peter Maydell]

On 16 November 2010 18:10, Anthony Liguori <address@hidden> wrote:
> On 11/16/2010 11:43 AM, Peter Maydell wrote:
>> Unfortunately these commits:
>> 2834c3e Add support for generating a systemtap tapset static probes
>> 4addb11 Add a DTrace tracing backend targetted for SystemTAP compatability
>
> What's your configure output?

I've attached it; the trace related bits are:
Trace backend     nop
Trace output file trace-<pid>

> I don't have the right environment to build with systemtap support, but
> --trace-backend=nop should work regardless.

I'm using the nop backend, yes.

I think the problem is that commit 2834c3e adds a target 'trace:' to the
Makefile.target which looks like it's intended to be a phony target. However
it isn't marked as such, so make actually tries to create a binary 'trace'
by falling back to its default rules (since there's a "trace.c" in the root
directory):

address@hidden:~/qemu-test/qemu/i386-softmmu$ make -n trace
echo "  CC    trace.o" && gcc -I/home/petmay01/qemu-test/qemu/slirp
-Werror -m64 -I. -I/home/petmay01/qemu-test/qemu -D_FORTIFY_SOURCE=2
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wendif-labels
-Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing
-fstack-protector-all -Wempty-body -Wnested-externs -Wformat-security
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration
-Wold-style-definition -Wtype-limits -DHAS_AUDIO -DHAS_AUDIO_CHOICE
-I/home/petmay01/qemu-test/qemu/fpu
-I/home/petmay01/qemu-test/qemu/tcg
-I/home/petmay01/qemu-test/qemu/tcg/i386  -DTARGET_PHYS_ADDR_BITS=32
-I.. -I/home/petmay01/qemu-test/qemu/target-i386 -DNEED_CPU_H     -MMD
-MP -MT trace.o -MF ./trace.d -O2 -g  -c -o trace.o
/home/petmay01/qemu-test/qemu/trace.c
echo "  LINK  trace" && gcc -I/home/petmay01/qemu-test/qemu/slirp
-Werror -m64 -I. -I/home/petmay01/qemu-test/qemu -D_FORTIFY_SOURCE=2
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wendif-labels
-Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing
-fstack-protector-all -Wempty-body -Wnested-externs -Wformat-security
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration
-Wold-style-definition -Wtype-limits -DHAS_AUDIO -DHAS_AUDIO_CHOICE
-I/home/petmay01/qemu-test/qemu/fpu
-I/home/petmay01/qemu-test/qemu/tcg
-I/home/petmay01/qemu-test/qemu/tcg/i386  -DTARGET_PHYS_ADDR_BITS=32
-I.. -I/home/petmay01/qemu-test/qemu/target-i386 -DNEED_CPU_H     -O2
-g  -Wl,--warn-common -m64 -g   -o trace trace.o -lrt -lpthread
-lutil -lcurl   -lncurses  -luuid -lpng -lsasl2 -lgnutls   -lSDL
-lX11  -laio -lm -lz

...and linking only trace.o into a binary 'trace' fails because
trace.c doesn't have a main() (or indeed any functions at all).

If I add a ".PHONY: trace" or change the "trace" target
name to "tracexyzzy" then this fixes the problem.

-- PMM

configure.out
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