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+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+x86-specific ELF Auxiliary Vectors
+==================================
+
+This document describes the semantics of the x86 auxiliary vectors.
+
+Introduction
+============
+
+ELF Auxiliary vectors enable the kernel to efficiently provide
+configuration-specific parameters to userspace. In this example, a program
+allocates an alternate stack based on the kernel-provided size::
+
+ #include <sys/auxv.h>
+ #include <elf.h>
+ #include <signal.h>
+ #include <stdlib.h>
+ #include <assert.h>
+ #include <err.h>
+
+ #ifndef AT_MINSIGSTKSZ
+ #define AT_MINSIGSTKSZ 51
+ #endif
+
+ ....
+ stack_t ss;
+
+ ss.ss_sp = malloc(ss.ss_size);
+ assert(ss.ss_sp);
+
+ ss.ss_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ;
+ ss.ss_flags = 0;
+
+ if (sigaltstack(&ss, NULL))
+ err(1, "sigaltstack");
+
+
+The exposed auxiliary vectors
+=============================
+
+AT_SYSINFO is used for locating the vsyscall entry point. It is not
+exported on 64-bit mode.
+
+AT_SYSINFO_EHDR is the start address of the page containing the vDSO.
+
+AT_MINSIGSTKSZ denotes the minimum stack size required by the kernel to
+deliver a signal to user-space. AT_MINSIGSTKSZ comprehends the space
+consumed by the kernel to accommodate the user context for the current
+hardware configuration. It does not comprehend subsequent user-space stack
+consumption, which must be added by the user. (e.g. Above, user-space adds
+SIGSTKSZ to AT_MINSIGSTKSZ.)