OpenWRT firmware for routers
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David Woodhouse 6eb63019af mediatek: mt7623: fix sysupgrade from vendor OpenWrt on UniElec U7623
This board ships with an ancient 14.07-based OpenWrt using block2mtd, and
the MBR partition table contains nonsense.

It is possible to sysupgrade to an upstream OpenWrt image, but the
legacy layout of the OpenWrt images start at 0xA00 in the eMMC, with
a raw uImage. The legacy OpenWrt image doesn't "own" the beginning
of the device, including the MBR and U-Boot.

This means that when a user upgrades to upstream OpenWrt, it doesn't
boot because it can't find the right partitions. So hard-code them on
the kernel's command line using CONFIG_CMDLINE_PARTITION (for block).

Additionally, the vendor firmware doesn't cope with images larger than
about 36MiB, because it only overwrites the contents of its "firmware"
MTD partition. The current layout of the legacy image wastes a lot of
space, allowing over 32MiB for the kernel and another 10MiB for the FAT
recovery file system which is only created as 3MiB. So pull those in
to allow 4¾ MiB for the kernel, 3MiB for recovery, and then we have over
20MiB for the root file system.

This doesn't affect the new images which ship with a full eMMC image
including a different MBR layout and a partition for U-Boot, because
our modern U-Boot can actually pass the command line to the kernel, and
the built-in one doesn't get used anyway.

Tested by upgrading from vendor OpenWrt to the current legacy image,
from legacy to itself, to the previous legacy layout, and then to
finally the full-system image.

This commit probably wants backporting to 19.07, which also doesn't
install over the vendor OpenWrt and doesn't even have a full-system
installation option.

Signed-off-by: David Woodhouse <>
4 years ago
.github build: Update README & github help 6 years ago
config build: Remove dependency of user space stack cookies from kernel 4 years ago
include kernel: bump 5.4 to 5.4.52 4 years ago
package mac80211: util: don't warn on missing sband iftype data 4 years ago
scripts build,json: fix compatibility with Python 3.5 4 years ago
target mediatek: mt7623: fix sysupgrade from vendor OpenWrt on UniElec U7623 4 years ago
toolchain toolchain: binutils: Use version 2.34 by default 4 years ago
tools tools/mkimage: create .itb file with read-access for group,other not just owner. 4 years ago
.gitattributes add .gitattributes to prevent the git autocrlf option from messing with CRLF/LF in files 12 years ago
.gitignore build: improve ccache support 4 years ago
BSDmakefile add missing copyright header 17 years ago merge: base: update base-files and basic config 6 years ago
LICENSE finally move buildroot-ng to trunk 8 years ago
Makefile build: improve ccache support 4 years ago
README build: switch to Python 3 5 years ago
feeds.conf.default feeds: add freifunk feed 4 years ago build: improve ccache support 4 years ago


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          |__| W I R E L E S S   F R E E D O M

This is the buildsystem for the OpenWrt Linux distribution.

To build your own firmware you need a Linux, BSD or MacOSX system (case
sensitive filesystem required). Cygwin is unsupported because of the lack
of a case sensitive file system.

You need gcc, binutils, bzip2, flex, python3.5+, perl, make, find, grep, diff,
unzip, gawk, getopt, subversion, libz-dev and libc headers installed.

1. Run "./scripts/feeds update -a" to obtain all the latest package definitions
defined in feeds.conf / feeds.conf.default

2. Run "./scripts/feeds install -a" to install symlinks for all obtained
packages into package/feeds/

3. Run "make menuconfig" to select your preferred configuration for the
toolchain, target system & firmware packages.

4. Run "make" to build your firmware. This will download all sources, build
the cross-compile toolchain and then cross-compile the Linux kernel & all
chosen applications for your target system.

	Your OpenWrt Community