src/kernel/linux/v4.14/arch/x86/xen/vdso.h - T103 - Gitiles

 /* Bit used for the pseudo-hwcap for non-negative segments.  We use
    bit 1 to avoid bugs in some versions of glibc when bit 0 is
    used; the choice is otherwise arbitrary. */
 #define VDSO_NOTE_NONEGSEG_BIT	1
	/* Bit used for the pseudo-hwcap for non-negative segments. We use
	bit 1 to avoid bugs in some versions of glibc when bit 0 is
	used; the choice is otherwise arbitrary. */
	#define VDSO_NOTE_NONEGSEG_BIT 1