[Linux][Compiler] Compilation fails with -no-runtime flag

[maximvl]

> cat hello.red 
Red/System []

a: 1
if a < 2 [ a: 2 ]

> red -c --no-runtime hello.red 

-=== Red Compiler 0.6.3 ===- 

Compiling /home/mvelesyuk/red/hello.red ...

Target: Linux 

Compiling to native code...
*** Red/System Compiler Internal Error: Script Error : Cannot use path on none! value 
*** Where: emit-epilog 
*** Near:  [if any [
fspec/5 = 'callback 
all [
attribs: compiler/get-attributes fspec/4 
any [find attribs 'cdecl find attribs 'stdcall]
]
] [
offset: locals-size + locals-offset 
emit #{8DA5} 
emit to-bin32 negate offset + 12 
emit #{5F} 
emit #{5E} 
emit #{5B}
] 
emit
] 

> red -c hello.red        

-=== Red Compiler 0.6.3 ===- 

Compiling /home/mvelesyuk/red/hello.red ...

Target: Linux 

Compiling to native code...
...compilation time : 318 ms
...linking time     : 14 ms
...output file size : 6640 bytes
...output file      : /home/mvelesyuk/red/hello 

[dockimbel]

--no-runtime is for Red/System programs only, it is meant for cases where you can't use the built-in runtime library and want/need to provide a specific one (for example: writing your own OS or for barebone embedded systems).

[PeterWAWood]

The supplied program though named Hello.red was in fact a Red/System program.

Should there be either a special target for such programs (e.g. -t em-i386, -t em-ARMel) or the --no-runtime option require a processor argument (e.g. --no-runtime i386, --no-runtime ARMhf)?

[ghost]

For generating runnable binaries using --no-runtime see #1772 (comment)

[sam-baravy]

Guys, the code above is an attempt to produce an object (or just flat) file to link it later into a boot loader. I didn't understand from your comments if it is possible at the moment. It wasn't intended to be runnable by itself.

[dockimbel]

Okay, I got confused by the .red suffix. Pure Red/System source files use .reds suffix.

On Windows, it compiles fine. Let me investigate why it fails on Linux.

[dockimbel]

Ok, it should compile fine now.

@sam-baravy Let me give you some extra info about that feature:

• The --no-runtime on Linux still generates an ELF executable with at least code and data segments, so just to be clear, it's not an object file in the C sense (.o).
• The --no-runtime has only been used so far for a prototype Arduino support, internally linked by Red's toolchain to a tiny pre-compiled binary runtime (less than a kilobyte IIRC).
• On Windows, we built specific support for compiling Windows drivers for a commercial project. We had plans for supporting also Linux kernel modules, but didn't have a use-case for it, so it wasn't built.

I haven't compiled a Linux kernel since 20 years, so I don't recall the image format, so I'm not sure you'll be able to use the currently emitted ELF file to make a bootable code from it. In any case, I suggest you add some extra compilation options (just guessing you'll need them):

• Turn PIC mode on, to avoid generating absolute addresses in code segment
• Set the base address for the code segment manually.

Here is how you can do set that from the header (passing those options on command-line is currently broken):

Red/System [
    config: [
        PIC?: yes
        base-address: 32768               ; 8000h
    ]
]

a: 1
if a < 2 [ a: 2 ]

The generated code layout looks like this. As you can see, the PIC mode is used, but initialization code for ebx is missing. I will add a fix for that tomorrow.

[sam-baravy]

@dockimbel Thank you for the fix and information. IMO, the issue is resolved.

Right now I'm doing some low-level programming in Red/System. Just for fun and as a proof of concept. I'll try to not steal too much your time, but come back with new bugs if they arise.

Waiting for the second fix you mentioned.

[dockimbel]

The PIC mode is now correctly initialized.

@sam-baravy Keep us informed of your progress on that (preferrably on our Gitter main chat room), I don't have much time to allocate for such features, but if it doesn't cost too much time, I'll be glad to enable generating bootable code/images using Red/System code. ;-)

Cheers!