主机为 ubuntu 14 x64 硬件： 优酷土豆宝 cpuMT7620A，内存128M，flash 32M
有2个源，用哪个也可以
git clone https://github.com/openwrt/openwrt.git
git clone https://git.openwrt.org/openwrt/openwrt.git
安装的插件
gcc, binutils, bzip2, flex, python, perl, make, find, grep, diff,
unzip, gawk, getopt, subversion, libz-dev
gcc 要求 4.8 以上
./scripts/feeds update -a
./scripts/feeds install -a
配置
make menuconfig
选择 mtk7620
Target System (MediaTek Ralink MIPS)
Subtarget (MT7620 based boards)
Target Profile (YOUKU YK1)
make -j 4
编译看不到编译信息
make V=99 -j 4
加上 V=99 参数看到具体信息，是下载不了，还是什么的错误
一共下载了2天时间。有的包还是手动下的。
编译以后全部文件有10个G 。
在路由器后台直接升级 squashfs-sysupgrade.bin 就可以了
需要装上界面
opkg update
opkg install luci
/etc/init.d/uhttpd enable
/etc/init.d/uhttpd start
更新 openwrt 19 2019-12-24
build_dir/hostpkg/libubox-2019-11-24-07413cce/json_script.c:124:3: error: missing initializer for field 'name' of 'struct blobmsg_policy' [-Werror=missing-field-initializers]
修改
/build_dir/hostpkg/libubox-2019-11-24-07413cce/CMakeLists.txt
-Werror 去掉即可，原因：存在 warning 当错误，导致编译不过。
更新 openwrt 19 2021-01-16
build_dir/hostpkg/expat-2.2.10/lib/xmlparse.c:109:4: error: #error You do not have support for any sources of high quality entropy enabled. For end user security, that is probably not what you want. Your options include: * Linux >=3.17 + glibc >=2.25 (getrandom): HAVE_GETRANDOM, * Linux >=3.17 + glibc (including <2.25) (syscall SYS_getrandom): HAVE_SYSCALL_GETRANDOM, * BSD / macOS >=10.7 (arc4random_buf): HAVE_ARC4RANDOM_BUF, * BSD / macOS (including <10.7) (arc4random): HAVE_ARC4RANDOM, * libbsd (arc4random_buf): HAVE_ARC4RANDOM_BUF + HAVE_LIBBSD, * libbsd (arc4random): HAVE_ARC4RANDOM + HAVE_LIBBSD, * Linux (including <3.17) / BSD / macOS (including <10.7) (/dev/urandom): XML_DEV_URANDOM, * Windows >=Vista (rand_s): _WIN32. If insist on not using any of these, bypass this error by defining XML_POOR_ENTROPY; you have been warned. If you have reasons to patch this detection code away or need changes to the build system, please open a bug. Thank you!
# error You do not have support for any sources of high quality entropy
去掉这个宏检查。