I downloaded the source files from the mega link. Then I followed the instructions from the 2g-iot manual to build the Androiid source. I am getting the following error:
"/bin/bash: mips-elf-gcc: command not found"

This error occurs when trying to compile the modem image.

Anyone experienced this?

Thanks,
SN

I was able to get around this build error by removing the 2G Modem support. I still plan to figure out the 2G Modem build errors at a later date.

To get the build working without 2g Modem support just make the following change to /device/rda/slt/BoardConfig.mk

# TARGET_NO_MODEM := false
TARGET_NO_MODEM := true

Thanks,
SN

You need to execute the following command
$ sudo tar -xzf ~/modem-cross-compiler-linux.tar.gz -C /opt$ ls /opt/cross-compiler
$ sudo chown -R root:root /opt/cross-compiler
$ sudo chmod +x /opt/cross-compiler/bin/*
$ sudo sh -c 'echo export PATH=$PATH:/opt/cross-compiler/bin >/etc/profile.d/cross-compiler.sh'
$ sudo sh -c 'echo /opt/cross-compiler/lib > /etc/ld.so.conf.d/cross-compiler.conf'
$ sudo ldconfig -v
$ sudo ldconfig -v | grep '/opt/cross-compiler/lib'
$ mips-elf-gcc -v

You can find it in the source code： modem-cross-compiler-linux.tar.gz

Would like to share my findings about XCPU part (modem).

XCPU comes from CoolSand, so tools needed for compiling are CSDTK3.8 and CSDTK4.2, you can find those over internet, if will be needed I have a copy.
Those tools are for Windows.
To get sources compiled I had to install both, used version 3.8 but had to update file srecmap.exe from version 4.2.
I had to find mkimage.exe and place it near srecmap.exe.
Modem sources are in SDK from OrangePi  , OrangePi-2g_Android/modem .
There is two versions for dual and single SIM.
And I had to update modem-src/soft/env/compilation/compilerules.mk file :
line 3279: srecmap -c ${MAP_FILE} -m ${FLSH_MODEL} ${HEX} ${BAS}_ ${STDOUT_NULL}
to
srecmap -c `cygpath -w ${MAP_FILE}` -m ${FLSH_MODEL} `cygpath -w ${HEX}` `cygpath -w ${BAS}_` ${STDOUT_NULL}

Similar changes need be done for mkimage use flags in the same file.
After those changes, create modem/output directory , and from modem source path execute:
./build_modem.sh system soft/ ../output/ ../../device/rda/etau/ Lensun_R635D_8810P release MODEM MyModemHAHA 0 phone

At this step I got working modem firmware, but with lack of SIM .
Solution for SIM visibility is:
in OrangePi_2G-IOT_Android/device/rda/etau/Lensun_R635D_8810P/target.def
need change
USER_SIM_ORDER ?= 1

That's all.

Edited by Pe3ucTop at 2020-7-9 20:06

Would be great to find original "modem-cross-compiler-linux.tar.gz" , may be someone have local copy of it ?
Links I found around are out of date and not working.
There is "modem-crosss-compiler-linux.tar.gz" file on original orange pi download site now (probably after Mart of this year).