1# SPDX-License-Identifier: GPL-2.0+ 2# Copyright (c) 2016 Google, Inc 3# Written by Simon Glass <sjg@chromium.org> 4# 5# Entry-type module for BSS padding for spl/u-boot-spl.bin. This padding 6# can be added after the SPL binary to ensure that anything concatenated 7# to it will appear to SPL to be at the end of BSS rather than the start. 8# 9 10import command 11import elf 12from entry import Entry 13from blob import Entry_blob 14import tools 15 16class Entry_u_boot_spl_bss_pad(Entry_blob): 17 """U-Boot SPL binary padded with a BSS region 18 19 Properties / Entry arguments: 20 None 21 22 This is similar to u_boot_spl except that padding is added after the SPL 23 binary to cover the BSS (Block Started by Symbol) region. This region holds 24 the various used by SPL. It is set to 0 by SPL when it starts up. If you 25 want to append data to the SPL image (such as a device tree file), you must 26 pad out the BSS region to avoid the data overlapping with U-Boot variables. 27 This entry is useful in that case. It automatically pads out the entry size 28 to cover both the code, data and BSS. 29 30 The ELF file 'spl/u-boot-spl' must also be available for this to work, since 31 binman uses that to look up the BSS address. 32 """ 33 def __init__(self, section, etype, node): 34 Entry_blob.__init__(self, section, etype, node) 35 36 def ObtainContents(self): 37 fname = tools.GetInputFilename('spl/u-boot-spl') 38 bss_size = elf.GetSymbolAddress(fname, '__bss_size') 39 if not bss_size: 40 self.Raise('Expected __bss_size symbol in spl/u-boot-spl') 41 self.SetContents(chr(0) * bss_size) 42 return True 43