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digitalmars.D - How can I use ldc2 and link to full runtime on arm with no OS

reply Dan Walmsley <dan walms.co.uk> writes:
I'm starting to make attempts to find out what is needed to make 
D finally work on low level embedded targets. I have been using 
LDC2, i compile each .d file to and .o file and link using 
arm-none-eabi-gcc. I have a demo available here: 
Www.github.com/vitalelement/stm32dblinky includes a linked script.

I was originally trying to have a minimal run time approach but 
having read a lot here I don't buy the argument that these 
targets cant run with GC. So id like to now link to the full run 
time if possible and try out the GC.

However there doesn't seem to be any guide on how to do this?

I need to know, how does the run time know which area of ram to 
use for heap? In c/c++ usually we use linked script to provide an 
area of ram for this.

How do I link in the run time and gc, etc?

Many thanks

Dan
Jun 20 2017
next sibling parent reply kinke <noone nowhere.com> writes:
On Tuesday, 20 June 2017 at 17:52:59 UTC, Dan Walmsley wrote:

 How do I link in the run time and gc, etc?


In your case, you firstly need to cross-compile druntime to your 
target. This means compiling most files in the src subdirectory 
of LDC's druntime [1], excluding obvious ones like 
src\test_runner.d, src\core\sys, src\core\stdcpp etc. There are 
also a bunch of C and assembly files which need to be 
cross-compiled with a matching gcc. You'll need to do this 
manually via something along these lines:

cross-gcc -c <.c files and .asm/S files>
ldc2 -mtriple=... -lib -betterC -release -boundscheck=off <.o 
files generated above> <list of D source modules> 
-of=libdruntime.a

Then try linking your minimal code against that druntime (and 
static C libs, as druntime is built on top of the C runtime, see 
[2]). Depending on what features you make use of in your code, 
you'll need to patch linked-in druntime modules to remove the OS 
dependencies and possibly reduce the C runtime dependencies as 
well.

[1] https://github.com/ldc-developers/druntime.
[2] 
http://forum.dlang.org/thread/mojmxbjwtfmioevuoggb forum.dlang.org
Jun 20 2017
parent reply Dan Walmsley <dan walms.co.uk> writes:
On Tuesday, 20 June 2017 at 19:44:46 UTC, kinke wrote:

 On Tuesday, 20 June 2017 at 17:52:59 UTC, Dan Walmsley wrote:

 How do I link in the run time and gc, etc?


 In your case, you firstly need to cross-compile druntime to 
 your target. This means compiling most files in the src 
 subdirectory of LDC's druntime [1], excluding obvious ones like 
 src\test_runner.d, src\core\sys, src\core\stdcpp etc. There are 
 also a bunch of C and assembly files which need to be 
 cross-compiled with a matching gcc. You'll need to do this 
 manually via something along these lines:

 cross-gcc -c <.c files and .asm/S files>
 ldc2 -mtriple=... -lib -betterC -release -boundscheck=off <.o 
 files generated above> <list of D source modules> 
 -of=libdruntime.a

 Then try linking your minimal code against that druntime (and 
 static C libs, as druntime is built on top of the C runtime, 
 see [2]). Depending on what features you make use of in your 
 code, you'll need to patch linked-in druntime modules to remove 
 the OS dependencies and possibly reduce the C runtime 
 dependencies as well.

 [1] https://github.com/ldc-developers/druntime.
 [2] 
 http://forum.dlang.org/thread/mojmxbjwtfmioevuoggb forum.dlang.org


when trying to compile I'm getting lots of errors like this one:

C:\dev\repos\druntime\src\gc\impl\manual\gc.d(28): Error: module 
config is in file 'gc\config.d' which cannot be read

import path[0] = 
C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import\ldc

import path[1] = 
C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import

Build Failed

any ideas what could be the cause?
Jun 21 2017
next sibling parent Dan Walmsley <dan walms.co.uk> writes:
On Wednesday, 21 June 2017 at 14:53:04 UTC, Dan Walmsley wrote:

 On Tuesday, 20 June 2017 at 19:44:46 UTC, kinke wrote:

 [...]


 when trying to compile I'm getting lots of errors like this one:

 C:\dev\repos\druntime\src\gc\impl\manual\gc.d(28): Error: 
 module config is in file 'gc\config.d' which cannot be read

 import path[0] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import\ldc

 import path[1] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import

 Build Failed

 any ideas what could be the cause?


and also:


LLVM ERROR: unsupported relocation on symbol
[CC 9/164]    [druntime]    convert.d

Build Failed

LLVM ERROR: unsupported relocation on symbol

after changing flags to:

-c -O0 -lib -betterC -release -boundscheck=off -march=thumb 
-mcpu=cortex-m4 -mtriple=thumb-none-linux-eabi
Jun 21 2017
prev sibling parent reply David Nadlinger <code klickverbot.at> writes:
On Wednesday, 21 June 2017 at 14:53:04 UTC, Dan Walmsley wrote:

 when trying to compile I'm getting lots of errors like this one:

 C:\dev\repos\druntime\src\gc\impl\manual\gc.d(28): Error: 
 module config is in file 'gc\config.d' which cannot be read

 import path[0] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import\ldc

 import path[1] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import

 Build Failed

 any ideas what could be the cause?


You are not adding druntime/src to the import path.

I'd suggest you focus on other things first, though. Having D's 
GC on a platform with less than 1 MiB RAM is a rather sketchy 
proposition.

  — David
Jun 21 2017
parent reply Dan Walmsley <dan walms.co.uk> writes:
On Wednesday, 21 June 2017 at 15:45:32 UTC, David Nadlinger wrote:

 On Wednesday, 21 June 2017 at 14:53:04 UTC, Dan Walmsley wrote:

 when trying to compile I'm getting lots of errors like this 
 one:

 C:\dev\repos\druntime\src\gc\impl\manual\gc.d(28): Error: 
 module config is in file 'gc\config.d' which cannot be read

 import path[0] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import\ldc

 import path[1] = 
 C:\Users\danw\AvalonStudio\AppData\Repos\AvalonStudio.Toolchains.LDC.win-x64.4.0.0-build2-alpha\content\bin\..\import

 Build Failed

 any ideas what could be the cause?


 You are not adding druntime/src to the import path.

 I'd suggest you focus on other things first, though. Having D's 
 GC on a platform with less than 1 MiB RAM is a rather sketchy 
 proposition.

  — David


My idea is to build the whole thing, see what the code size and 
performance is, and then one by one reduce things down as needed.

Starting from nothing so far has been a bit of a none starter!
Jun 21 2017
parent reply David Nadlinger <code klickverbot.at> writes:
On Wednesday, 21 June 2017 at 16:10:41 UTC, Dan Walmsley wrote:

 My idea is to build the whole thing, see what the code size and 
 performance is, and then one by one reduce things down as 
 needed.

 Starting from nothing so far has been a bit of a none starter!


This way, you'll end up having to port all of druntime to your 
target, though, only to then throw away considerable amounts of 
work that went into the parts you don't want to use.

I don't think the notion of implementing a feature being easier 
than understanding how to rip it out is very realistic.

  — David
Jun 21 2017
parent Mike <none none.com> writes:
On Wednesday, 21 June 2017 at 22:11:04 UTC, David Nadlinger wrote:


 This way, you'll end up having to port all of druntime to your 
 target, though, only to then throw away considerable amounts of 
 work that went into the parts you don't want to use.


You are correct, but if you omit certain parts of the runtime, 
you end up with things like these:

https://github.com/ldc-developers/ldc/issues/2174
https://github.com/ldc-developers/ldc/issues/552
https://github.com/ldc-developers/ldc/issues/781

The compiler and druntime are too tightly-coupled to make 
pay-as-you-go D development practical.  Some support to remedy 
that would be most welcome.

Mike
Jun 21 2017
prev sibling parent David Nadlinger <code klickverbot.at> writes:
On Tuesday, 20 June 2017 at 17:52:59 UTC, Dan Walmsley wrote:

 I need to know, how does the run time know which area of ram to 
 use for heap?


It uses C's malloc/calloc().

  — David
Jun 20 2017