[Xen-devel] Compile errors with gcc 4.8

[M A Young <m.a.young@xxxxxxxxxxxx>]

Fedora rawhide has just moved onto gcc 4.8, and I have had to apply the 
attached patch to get it to build (I constructed the patch against 4.2.1 
but I believe it will apply to xen-unstable).
There are two types of problem, the first is from 
xen/common/compat/memory.c where the error is
memory.c: In function 'compat_memory_op':
/builddir/build/BUILD/xen-4.2.1/xen/include/public/arch-x86/xen.h:35:33: 
error: typedef '__guest_handle_const_compat_memory_exchange_t' locally 
defined but not used [-Werror=unused-local-typedefs]
     typedef struct { type *p; } __guest_handle_ ## name
                                 ^
/builddir/build/BUILD/xen-4.2.1/xen/include/public/arch-x86/xen.h:43:5: 
note: in expansion of macro '___DEFINE_XEN_GUEST_HANDLE'
     ___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
     ^
/builddir/build/BUILD/xen-4.2.1/xen/include/public/arch-x86/xen.h:44:41: 
note: in expansion of macro '__DEFINE_XEN_GUEST_HANDLE'
 #define DEFINE_XEN_GUEST_HANDLE(name)   __DEFINE_XEN_GUEST_HANDLE(name, 
name)
                                         ^
memory.c:261:13: note: in expansion of macro 'DEFINE_XEN_GUEST_HANDLE'
             DEFINE_XEN_GUEST_HANDLE(compat_memory_exchange_t);
             ^

so we are defining something that isn't used.

Secondly gcc 4.8 objects to lines like

memset(ctxt, 0, sizeof(ctxt));

where I think you are just zeroing a pointer's worth of memory. There are 
a few cases of this in the xen code fixed in the patch, and I am also 
suspicious of line 630 of 
stubdom/grub-upstream/stage2/fsys_reiserfs.c which is
memset (INFO->blocks, 0, sizeof (INFO->blocks));

which is noted in the build log but not flagged as an error.

        Michael Young

Attachment: gcc48.build.patch
Description: Text document

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