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https://github.com/brain-hackers/u-boot-brain
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a0dcaf2049
At present if this function tries to update the contents such that the size changes, it raises an error. We plan to add the ability to change the size of entries after packing is completed, since in some cases it is not possible to determine the size in advance. An example of this is with a compressed device tree, where the values of the device tree change in SetCalculatedProperties() or ProcessEntryContents(). While the device tree itself does not change size, since placeholders for any new properties have already bee added by AddMissingProperties(), we cannot predict the size of the device tree after compression. If a value changes from 0 to 0x1234 (say), then the compressed device tree may expand. As a first step towards supporting this, make ProcessContentsUpdate() return a value indicating whether the content size is OK. For now this is always True (since otherwise binman raises an error), but later patches will adjust this. Signed-off-by: Simon Glass <sjg@chromium.org>
77 lines
2.9 KiB
Python
77 lines
2.9 KiB
Python
# SPDX-License-Identifier: GPL-2.0+
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# Copyright (c) 2018 Google, Inc
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# Written by Simon Glass <sjg@chromium.org>
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"""Entry-type module for an image header which points to the FDT map
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This creates an 8-byte entry with a magic number and the offset of the FDT map
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(which is another entry in the image), relative to the start or end of the
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image.
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"""
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import struct
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from entry import Entry
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import fdt_util
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IMAGE_HEADER_MAGIC = b'BinM'
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class Entry_image_header(Entry):
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"""An entry which contains a pointer to the FDT map
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Properties / Entry arguments:
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location: Location of header ("start" or "end" of image). This is
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optional. If omitted then the entry must have an offset property.
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This adds an 8-byte entry to the start or end of the image, pointing to the
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location of the FDT map. The format is a magic number followed by an offset
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from the start or end of the image, in twos-compliment format.
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This entry must be in the top-level part of the image.
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NOTE: If the location is at the start/end, you will probably need to specify
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sort-by-offset for the image, unless you actually put the image header
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first/last in the entry list.
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"""
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def __init__(self, section, etype, node):
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Entry.__init__(self, section, etype, node)
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self.location = fdt_util.GetString(self._node, 'location')
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def _GetHeader(self):
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image_pos = self.GetSiblingImagePos('fdtmap')
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if image_pos == False:
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self.Raise("'image_header' section must have an 'fdtmap' sibling")
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elif image_pos is None:
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# This will be available when called from ProcessContents(), but not
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# when called from ObtainContents()
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offset = 0xffffffff
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else:
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image_size = self.section.GetImageSize() or 0
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base = (0 if self.location != 'end' else image_size)
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offset = (image_pos - base) & 0xffffffff
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data = IMAGE_HEADER_MAGIC + struct.pack('<I', offset)
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return data
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def ObtainContents(self):
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"""Obtain a placeholder for the header contents"""
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self.SetContents(self._GetHeader())
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return True
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def Pack(self, offset):
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"""Special pack method to set the offset to start/end of image"""
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if not self.offset:
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if self.location not in ['start', 'end']:
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self.Raise("Invalid location '%s', expected 'start' or 'end'" %
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self.location)
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image_size = self.section.GetImageSize() or 0
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self.offset = (0 if self.location != 'end' else image_size - 8)
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return Entry.Pack(self, offset)
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def ProcessContents(self):
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"""Write an updated version of the FDT map to this entry
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This is necessary since image_pos is not available when ObtainContents()
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is called, since by then the entries have not been packed in the image.
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"""
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return self.ProcessContentsUpdate(self._GetHeader())
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