Re: [Xen-devel] HVM domains crash after upgrade from XEN 4.5.1 to 4.5.2

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.11.15 at 20:51, <ariel.atom2@xxxxxxxxxx> wrote:
> In terms of non-standard options passed to gcc I have tried to make sense of 
> what flags are actually being used during the build process. I am not 
> absolutely sure, but I think the options passed to gcc are as follows:
> 
> I do have system wide flags which are used for non-debug builds:
> CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"
> CXXFLAGS="${CFLAGS}"
> LDFLAGS="-Wl,-O1 -Wl,--as-needed"
> 
> for builds with debug symbols (using splitdebug) there are system wide 
> overrides as follows:
> CFLAGS="-march=native -O2 -pipe -ggdb"
> CXXFLAGS="${CFLAGS}"
> LDFLAGS: I'd assume that this inherits its value from the system wide 
> setting of LDFLAGS
> 
> for xen (the hypervisor) the build system seems to do the following:
> CFLAGS="" (i.e. unset CFLAGS)
> to me this indicates that the rest stays untouched (i.e. either standard or 
> debug flags)
> 
> for xen-tools (includes e.g. hvmloader) the build system appears to to the 
> following:
> CFLAGS="" (i.e. unset CFLAGS)
> CXXFLAGS="${CXXFLAGS} -fno-strict-overflow"
> LDFLAGS="" (i.e. unset LDFLAGS)
> 
> So I think there's probably nothing really fancy in my options to gcc.

What you list above seems pretty normal indeed. However, why don't
you simply look at the options actually passed to gcc when building the
hypervisor. And you should also not forget that your distro's gcc build
itself may have certain non-standard option settings. For the odd
stack accesses at function entry I think you should be able to see
whether this is a compiler default by looking at some random, not
overly trivial object file known to have been compiled by the exact
same compiler.

Jan


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