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Re: semantic error: not accessible at this address
- From: Vincent Bernat <bernat at luffy dot cx>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: systemtap at sourceware dot org
- Date: Sat, 28 Sep 2013 18:55:04 +0200
- Subject: Re: semantic error: not accessible at this address
- Authentication-results: sourceware.org; auth=none
- References: <87ioxmf2e9 dot fsf at guybrush dot luffy dot cx> <y0mvc1mt0k7 dot fsf at fche dot csb> <8738opg9ym dot fsf at guybrush dot luffy dot cx> <20130927230432 dot GA32221 at redhat dot com> <87wqm1etsz dot fsf at guybrush dot luffy dot cx> <20130927232529 dot GB32221 at redhat dot com> <87pprtesfe dot fsf at guybrush dot luffy dot cx> <20130928000247 dot GC32221 at redhat dot com> <871u49e68v dot fsf at guybrush dot luffy dot cx> <20130928124645 dot GA17249 at redhat dot com>
â 28 septembre 2013 14:46 CEST, "Frank Ch. Eigler" <fche@redhat.com>Â:
>> [...]
>> So, no "-mfentry" in "producer" variable. Is that expected?
>
> Aha, good catch. That was one of the safeguards we dropped into
> the stap code, but it relies on the CFLAGS=-grecord-gcc-switches.
> Would you be interested in adding code to that function to suppot
> a PR15123_ASSUME_MFENTRY-ish environment variable, that bypasses
> that subtest?
I have sent a proposition of patch (that works for me) but maybe you
prefer that I go through the bugzilla?
I am also concerned that a global environment variable for this would be
unsafe if you have to debug a combination of binaries compiled with and
without -mfentry (a kernel and some userland programs). I will just
recompile the kernel with CFLAGS=-grecord-gcc-switches. This seems
safer.
I can also advocate to Debian and Ubuntu to use this CFLAGS for future
kernel releases. Is there any drawback to this flag (I assume not)? Is
it still useful when GCC version is fixed? I mean, can we assume that we
will run in future GCC bugs and that will help to workaround them in the
future?
Thanks for the troubleshooting!
--
printk("Penguin %d is stuck in the bottle.\n", i);
2.0.38 /usr/src/linux/arch/sparc/kernel/smp.c