arch/arm/lib/bss.c

/*
 * Copyright 2013 Albert ARIBAUD <albert.u.boot@aribaud.net>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

/**
 * These two symbols are declared in a C file so that the linker
 * uses R_ARM_RELATIVE relocation, rather than the R_ARM_ABS32 one
 * it would use if the symbols were defined in the linker file.
 * Using only R_ARM_RELATIVE relocation ensures that references to
 * the symbols are correct after as well as before relocation.
 *
 * We need a 0-byte-size type for these symbols, and the compiler
 * does not allow defining objects of C type 'void'. Using an empty
 * struct is allowed by the compiler, but causes gcc versions 4.4 and
 * below to complain about aliasing. Therefore we use the next best
 * thing: zero-sized arrays, which are both 0-byte-size and exempt from
 * aliasing warnings.
 */

char __bss_start[0] __attribute__((used, section(".__bss_start")));
char __bss_end[0] __attribute__((used, section(".__bss_end")));