1# SPDX-License-Identifier: GPL-2.0+ 2# Copyright 2021 Google LLC 3# Written by Simon Glass <sjg@chromium.org> 4# 5# Entry-type module for BSS padding for tpl/u-boot-tpl.bin. This padding 6# can be added after the TPL binary to ensure that anything concatenated 7# to it will appear to TPL to be at the end of BSS rather than the start. 8# 9 10from binman import elf 11from binman.entry import Entry 12from binman.etype.blob import Entry_blob 13from u_boot_pylib import tools 14 15class Entry_u_boot_tpl_bss_pad(Entry_blob): 16 """U-Boot TPL binary padded with a BSS region 17 18 Properties / Entry arguments: 19 None 20 21 This holds the padding added after the TPL binary to cover the BSS (Block 22 Started by Symbol) region. This region holds the various variables used by 23 TPL. It is set to 0 by TPL when it starts up. If you want to append data to 24 the TPL image (such as a device tree file), you must pad out the BSS region 25 to avoid the data overlapping with U-Boot variables. This entry is useful in 26 that case. It automatically pads out the entry size to cover both the code, 27 data and BSS. 28 29 The contents of this entry will a certain number of zero bytes, determined 30 by __bss_size 31 32 The ELF file 'tpl/u-boot-tpl' must also be available for this to work, since 33 binman uses that to look up the BSS address. 34 """ 35 def __init__(self, section, etype, node): 36 super().__init__(section, etype, node) 37 38 def ObtainContents(self): 39 fname = tools.get_input_filename('tpl/u-boot-tpl') 40 bss_size = elf.GetSymbolAddress(fname, '__bss_size') 41 if bss_size is None: 42 self.Raise('Expected __bss_size symbol in tpl/u-boot-tpl') 43 self.SetContents(tools.get_bytes(0, bss_size)) 44 return True 45