On Mon, 24 Aug 2026 at 14:31, Frager, Neal <[email protected]> wrote: > > AMD General > > Hi Peter, > > > > > Hi Stewart, > > > > > The -I$(XEN_ROOT)/tools/include added to QEMU's extra-cflags causes > > > __XEN_INTERFACE_VERSION__ to be defined before xen_native.h is included, > > > triggering an include-order assertion. Downgrade to a warning since the > > > version is consistent in cross-compile. > > > Ref: https://github.com/qemu/qemu/commit/e2abfe5ec6 > > > > This is a buildroot issue, so I don't believe it's necessary to fix from > > > the > > > qemu side. > > > > I am not sure I fully agree here. While this is a buildroot identified > > issue, > > there could be other use cases for __XEN_INTERFACE_VERSION__ to be defined > > before xen_native.h is included. > > > But what, though? > > > And what we have found is that if > > __XEN_INTERFACE_VERSION__ to be defined before xen_native.h is included, it > > is not a hard error. For buildroot, the qemu works just fine in spite of > > this. > > > > I think that just means you got lucky. Either there is a hard requirement > > for one header to be included before the other (in which case it must > > be a #error, and whatever is causing the mis-ordering to happen must be > > fixed), or it's fine for the ordering to be either way (in which case it > > doesn't even need to be a #warning). > > From my view, the order the header files are included does not matter, and > this should not be an error. I agree with removing the warning as well, if > that is what we all agree on in the end.
The rationale for the header ordering is in the comment in include/hw/xen/xen.h: /* * C files using Xen toolstack libraries will have included those headers * already via xen_native.h, and having __XEM_TOOLS__ defined will have * automatically set __XEN_INTERFACE_VERSION__ to the latest supported * by the *system* Xen headers which were transitively included. * * C files which are part of the internal emulation, and which did not * include xen_native.h, may need this defined so that the Xen headers * imported to include/hw/xen/interface/ will expose the appropriate API * version. * * This is why there's a rule that xen_native.h must be included first. */ ...basically, if something doesn't include xen_native.h before xen.h then __XEN_INTERFACE_VERSION__ can end up defined to the wrong thing. (Disclaimer: I'm not a Xen expert, I'm just applying Chesterton's Fence.) thanks -- PMM
