Re: [Xen-devel] Fix core dumps of guests > 2 GB in size on i386

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

On Fri, Nov 17, 2006 at 09:52:15AM +0000, Keir Fraser wrote:
> On 15/11/06 22:02, "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote:
> 
> > The attached patch adds the O_LARGEFILE flag when opening the file. It
> > is also neccessary to add additional CFLAGS & LDFLAGS to enable use of
> > the POSIX Largefile  standard.  There are two ways to enable LFS support,
> > in implicit mode all types, functions & macros are automatically changed
> > to the 64 bit variants at compile time - this however changes the ABI
> > contract - eg size_t is now 64-bits instead of 32.
> 
> I like the implicit method. I think it's unlikely to bite us. A lot of tools
> subdirs are defining _FILE_OFFSET_BITS=64 anyway (and not using getconf!).
> I'll provide a portable common CFLAGS/LDFLAGS addition in tools/Rules.mk.

Well there are two methods in libxc which expose a size_t argument so the 
implicit method will break ABI changing these from 32 to 64 bits.

xenctrl.h:int xc_tbuf_enable(int xc_handle, size_t cnt, unsigned long *mfn,
xenctrl.h:int xc_acm_op(int xc_handle, int cmd, void *arg, size_t arg_size);

They are probably only called from other apps / libraries in the tools/
dir, so perhaps we don't care about ABI breakage in these two functions.

Must make sure the python binding is still working correctly though because
a 64-bit size_t on 32-bit arch will no longer fit in Python's native Int
type - will have to switch to Long

Regards,
Dan.
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