Structure assignments (e.g., struct foo x = y) sometimes get turned
into calls to memcpy() by GCC. It doesn't run the emitted memcpy()
through CPP so our macro-based implementation in the header files
doesn't get used. We therefore *always* have the implementation in
common/string.c as a "fall back".
I think some flag like '-ffreestanding' is supposed to avoid this
behaviour, but it's a pretty small issue and I don't know whether that
flag could have other unfortunate side effects.
-- Keir
PS. If you really do want a non-macro implementation of memcpy() for
IA64 then we can add __HAVE_ARCH_MEMCPY for you. We just won't define
that for x86, and we cannot remove the #undef.
> Perhaps someone who is smarter (or at least has more
> compiler/linker knowledge than me :-) can solve this
> bizarre problem:
>
> I have been annoyed for some time with a hack that's
> in xen/common/string.c... For the routine memcpy(),
> there is an #undef right before it. Why not do
> this properly and use the #ifndef __HAVE_ARCH_MEMCPY
> around it, like all the other routines? So I tried
> it. And got an undefined reference reported by the
> linker from arch/x86/vmx.o.
>
> Looking at arch/x86/vmx.c, there's no reference to
> memcpy. And if you look at the output from cpp, there's
> no reference to memcpy. If you add a #include
> for <xen/string.h> after <xen/lib.h>, it doesn't
> fix anything.
>
> To try to force the compiler to tell me where the
> problem lay, AHA, I added a line at the beginning
> of the source:
>
> void memcpy(void) {}
>
> thinking that the compiler would surely report a
> mismatch. It didn't and the compile/link succeeds!
>
> Clearly adding this line is not a nice solution.
> Can anyone come up with a better one? (Other than
> just leaving string.c as is...) Please try your
> solution yourself... I tried a few and couldn't find
> one that worked. If you find one, kindly reply to
> this post.
>
> Maybe I'm just tired....
>
> Dan
>
>
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-=- MIME -=-
Perhaps someone who is smarter (or at least has more
compiler/linker knowledge than me :-) can solve this
bizarre problem:
I have been annoyed for some time with a hack that's
in xen/common/string.c... For the routine memcpy(),
there is an #undef right before it. Why not do
this properly and use the #ifndef __HAVE_ARCH_MEMCPY
around it, like all the other routines? So I tried
it. And got an undefined reference reported by the
linker from arch/x86/vmx.o.
Looking at arch/x86/vmx.c, there's no reference to
memcpy. And if you look at the output from cpp, there's
no reference to memcpy. If you add a #include
for <xen/string.h> after <xen/lib.h>, it doesn't
fix anything.
To try to force the compiler to tell me where the
problem lay, AHA, I added a line at the beginning
of the source:
void memcpy(void) {}
thinking that the compiler would surely report a
mismatch. It didn't and the compile/link succeeds!
Clearly adding this line is not a nice solution.
Can anyone come up with a better one? (Other than
just leaving string.c as is...) Please try your
solution yourself... I tried a few and couldn't find
one that worked. If you find one, kindly reply to
this post.
Maybe I'm just tired....
Dan
-------------------------------------------------------
The SF.Net email is sponsored by: Beat the post-holiday blues
Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel
-------------------------------------------------------
The SF.Net email is sponsored by: Beat the post-holiday blues
Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
_______________________________________________
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