[Bug translator/25994] New: inproper order of PATH set cause wrong unexpected gcc used

[Bug translator/25994] New: inproper order of PATH set cause wrong unexpected gcc used

[xuchunmei at linux dot alibaba.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

            Bug ID: 25994
           Summary: inproper order of PATH set cause wrong unexpected gcc
                    used
           Product: systemtap
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: translator
          Assignee: systemtap at sourceware dot org
          Reporter: xuchunmei at linux dot alibaba.com
  Target Milestone: ---

Created attachment 12541
  --> https://sourceware.org/bugzilla/attachment.cgi?id=12541&action=edit
add default "/usr/bin:/bin" after $PATH

My use case is like this, I install gcc-4.8.5 and devtoolset-9-gcc,
while I set the PATH by "source /opt/rh/devtoolset-9/enable" to use
gcc-9, but when I use "stap test.stap", I always get compile errors
for "gcc: error: unrecognized command line option
‘-fpatchable-function-entry=2’", the option
‘-fpatchable-function-entry=2’ is not supported by gcc-4.8.5 but
supported by gcc-9.
The stap process building always use gcc-4.8.5 from /usr/bin not from
the first path of PATH, such as /opt/rh/devtoolset-9/root/usr/bin/gcc.

As I think the default /usr/bin:/bin should be added after $PATH.

I add an attachment to fix it, please have a review.

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fche at redhat dot com

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> ---
The problem is that for systemtap to build kernel modules compatible with the
system kernel, it must use the same compiler.  Jumping between major versions
can create incompatible modules, whether enforced by symbol versioning type
metadata, or undetected inconsistencies in kernel struct declarations.

Any idea where those -fpatchable-function-entry=2 cflags are coming from? 
Maybe we can nuke those from within stap more properly.

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[xuchunmei at linux dot alibaba.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

--- Comment #2 from xuchunmei <xuchunmei at linux dot alibaba.com> ---
(In reply to Frank Ch. Eigler from comment #1)
> The problem is that for systemtap to build kernel modules compatible with
> the system kernel, it must use the same compiler.  Jumping between major
> versions can create incompatible modules, whether enforced by symbol
> versioning type metadata, or undetected inconsistencies in kernel struct
> declarations.
> 
> Any idea where those -fpatchable-function-entry=2 cflags are coming from? 
> Maybe we can nuke those from within stap more properly.

yes, My kernel is build with devtoolset-9-gcc, and systemtap is also build with
devtoolset-9, when I use systemtap I want to use gcc which is
/opt/rh/devtoolset-9/root/usr/bin/gcc not /usr/bin/gcc.

the "-fpatchable-function-entry=2" is from arch/arm64/Makefile:

ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
  CC_FLAGS_FTRACE := -fpatchable-function-entry=2
endif

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[xuchunmei at linux dot alibaba.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

xuchunmei <xuchunmei at linux dot alibaba.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xuchunmei at linux dot alibaba.com

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

--- Comment #3 from Frank Ch. Eigler <fche at redhat dot com> ---
> yes, My kernel is build with devtoolset-9-gcc

Ahh, interesting.

Try: 
   # scl enable .... bash
   # stap -B CC=/opt/rh/...../bin/gcc  <options>

The -B option passes through kbuild make options.

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[xuchunmei at linux dot alibaba.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

--- Comment #4 from xuchunmei <xuchunmei at linux dot alibaba.com> ---
(In reply to Frank Ch. Eigler from comment #3)
> > yes, My kernel is build with devtoolset-9-gcc
> 
> Ahh, interesting.
> 
> Try: 
>    # scl enable .... bash
>    # stap -B CC=/opt/rh/...../bin/gcc  <options>
> 
> The -B option passes through kbuild make options.

ok,I try it, and it works, thanks.

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[Bug translator/25994] inproper order of PATH set cause wrong unexpected gcc used

[xuchunmei at linux dot alibaba.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=25994

xuchunmei <xuchunmei at linux dot alibaba.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |WORKSFORME

--- Comment #5 from xuchunmei <xuchunmei at linux dot alibaba.com> ---
it is not a problem, can use -B option to set kbuild make options

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