How to install arm-none-eabi-gdb on Ubuntu 20.04 LTS (Focal Fossa)

I tried to install arm-none-eabi-gdb as a part of gcc-arm-embedded. I added PPA:

sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa

and executed:

sudo apt install gcc-arm-embedded 

It responded with:

Err:8 http://ppa.launchpad.net/team-gcc-arm-embedded/ppa/ubuntu focal Release
  404  Not Found [IP: 91.189.95.83 80]

As far as I understand - gcc-arm-embedded doesn't have a version for Ubuntu 20. So I've changed release version for this PPA in Software & Updates to bionic so that I can avoid error 404.

Even though ubuntu 20 has libisl22, now I have unmet dependencies when I try to install gcc-arm-embedded:

The following packages have unmet dependencies:
 gcc-arm-embedded : Depends: libisl15 (>= 0.15) but it is not installable
E: Unable to correct problems, you have held broken packages.

I was unable to find a way to install requested version of libisl, as apt offers only two versions - libisl22 and libisl-dev and both are not accepted by installer.

I need advice on how to install arm-none-eabi-gdb. Thank you!

It turned out that ARM decided to make our life easier (sarcasm) by deprecating the use of PPA - their page at launchpad now has an anouncement: "... all new binary and source packages will not be released on Launchpad henceforth ...".

So, to make use of their latest arm-none-eabi-gdb you have to install gcc-arm-embedded manually.

Remove arm-none-eabi-gcc from your system:

sudo apt remove gcc-arm-none-eabi

Download latest version (Linux x86_64 Tarball) from their website, check its MD5. Unpack it into some directory. I used /usr/share/ :

sudo tar xjf gcc-arm-none-eabi-your-version.bz2 -C /usr/share/

Create links so that binaries are accessible system-wide:

sudo ln -s /usr/share/gcc-arm-none-eabi-your-version/bin/arm-none-eabi-gcc /usr/bin/arm-none-eabi-gcc 
sudo ln -s /usr/share/gcc-arm-none-eabi-your-version/bin/arm-none-eabi-g++ /usr/bin/arm-none-eabi-g++
sudo ln -s /usr/share/gcc-arm-none-eabi-your-version/bin/arm-none-eabi-gdb /usr/bin/arm-none-eabi-gdb
sudo ln -s /usr/share/gcc-arm-none-eabi-your-version/bin/arm-none-eabi-size /usr/bin/arm-none-eabi-size

Install dependencies. ARM's "full installation instructions" listed in readme.txt won't tell you what dependencies are - you have to figure it out by trial and error. In my system I had to manually create symbolic links to force it to work:

sudo apt install libncurses-dev
sudo ln -s /usr/lib/x86_64-linux-gnu/libncurses.so.6 /usr/lib/x86_64-linux-gnu/libncurses.so.5
sudo ln -s /usr/lib/x86_64-linux-gnu/libtinfo.so.6 /usr/lib/x86_64-linux-gnu/libtinfo.so.5

Check if it works:

arm-none-eabi-gcc --version
arm-none-eabi-g++ --version
arm-none-eabi-gdb --version
arm-none-eabi-size --version