Notes on building m6809-gdb for use with XRoar

Ciaran has a page up on his local build of an older version of gdb for working with 6809 and XRoar at

https://www.6809.org.uk/dragon/m6809-gdb.shtml

I am running Ubuntu, I think it's 18 (need to upgrade that sometime, I suppose, but no rush.)

I'm building XRoar from Ciaran's repository and installing it in my user-local executables directory. So the dependencies for XRoar were already installed when I started. 

The first time I tried to clone Ciaran's repository for m6809-gdb, network traffic just kept git from being able to load anything. Had to wait and try later, meaning today.

It's about 300 or 400 MB, and it's not a terribly time-consuming build, in the range of thirty minutes with a reasonable workstation configuration and broadband connection.

Following his instructions, i did the configure with the recommended parameters, and it got stuck part-way through. Couldn't find my Ada or flex; and then other peculiarities of my OS configuration got it stuck without those. (Thought I had both installed, but a quick check showed they weren't.) So, ...

I logged out of my working user and logged in to my admin user and got the most recent updates with Ubuntu's apt tool. (Where it's apt-get on Debian, it's just apt on Ubuntu, but pretty much similar. apt update, then apt upgrade.)

Then I looked around for Ada and flex. They are a little hard to find, because apt search and man -k both throw a lot of false-positives up there.

Ada -- the package on Ubuntu is gnat. Gnat-8 was available for my OS, but I loaded the default gnat, which turned out to be gnat-7:

sudo apt install gnat

Flex -- no, this is not that Flex, the old Flex operating system for 6800 and 6809. It is also not Digital Research's FlexOS. (Weren't there trademark issues with that?) Nor was it ...

Flex in this case is the fast lexical analyser generator, a re-implementation of the lex low-level parser (lexer) generator that was used with Yet Another Compiler Compiler (yacc) in putting together the early C compilers during the birth of Unix and C. The package name in Ubuntu is flex, so

sudo apt install flex

I remembered there were also messages about bison, so while I was at it I got that, too:

sudo apt install bison

(Yeah, bison is a re-implementation of yacc. Puns all around.)

When I logged back into my workstation user, the build process got stuck with cached configuration that said I didn't have bison. 

Make clean and several other of the usual methods didn't clear that, and I couldn't find config.cache to delete. So I just deleted the whole directory and started over with the git clone step.

This time, it successfully built.

Knowing that it built okay, I did a make clean and re-ran the configure step with a prefix option:

 --prefix=/home/myuser/local/mybin

(Not my real file system structure.) My login name in the above would be 

myuser

and my user-local place for keeping binaries in the above would be 

~/local/mybin

Running the make and make install steps after this configuration option is set allows me to run m6809-dbg when I'm logged in as myuser, but keeps it out of the general system executables. (I also do this with my own asm68c assembler, FWIW.)

Notes on running gdb:

• b *0x3971 to set breakpoint at 0x3971 without symbols
  
• ni (next instruction) to single-step
• info registers to show CPU registers
• c to continue