Gentoo's Bugzilla –
Attachment 577084 Details for
Bug 686172app-emulation/xen-tools-4.12.0-r2 - In file included from core/dummy_sanboot.c:33: include/ipxe/uri.h:178:12: error: taking address of packed member of ‘struct uri’ may result in an unaligned pointer value [-Werror=address-of-packed-member]