595088be09
All we need to provide to C at this point is a region in memory dedicated to its stack. This is done by allocating a region in .bss and pushing its start address to esp. Since the multiboot spec says it is not safe to rely on the initial stack provided by the bootloader, this patch provides our own stack. Galileo boards have 512Kb of SRAM and 256Mb of DDR3 RAM, so providing 8kb as a start seems safe. Moreover, stack sizes are very application-oriented so it may be too early to provide a bigger (or smaller) stack.
59 lines
2 KiB
ArmAsm
59 lines
2 KiB
ArmAsm
/*
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* Copyright (C) 2015, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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# Kernel
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.set STACK_SIZE, 8192
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# Multiboot
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.set MAGIC_NUMBER, 0x1BADB002
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.set FLAGS, 0x0
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.set CHECKSUM, -MAGIC_NUMBER
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.section .multiboot
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.align 4
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.long MAGIC_NUMBER
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.long FLAGS
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.long CHECKSUM
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# Reserve space for the C stack.
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.lcomm c_stack, STACK_SIZE
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.section .text
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.global start
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start:
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cli
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movl $(c_stack + STACK_SIZE), %esp
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call main
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/* We're not expected to return from main(). But if we do we halt */
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cli
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halt: hlt
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jmp halt
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