Peal: Palm ELF ARM Loader

Peal is an ELF postlinker and loader for Palm OS. It allows ARM code to use global variables and function pointers without restriction.

Peal version 2005-4-14
tar.gz archive (39 KB)
zip archive (68 KB)

New since version 2004-12-29:

Added support for C++ static constructors and destructors.
Downgraded postlinker's alignment error to a warning because some code like YAHM unnecessarily specifies large .text alignment.

See the release history for older versions and change logs.

Peal is distributed under a BSD-style license. See the README for complete license information.

Features supported by Peal and Peal-loaded ARM code:

Global variables
Function pointers
Automatic handling of code segments larger than 64 KB - no manual segmentation needed
Multiple entry point functions
Access to global variables from m68k code
Minimum memory usage - code and read-only data are not copied to feature memory or the heap
Thumb instruction set and ARM/Thumb interworking

Peal is substantially UNTESTED. It may crash, generate incorrect ARM global data, or modify random memory locations at runtime.
Peal has some support for C++ code, but it is even less tested.
Peal does not provide support for arbitrary ARM-ELF code. Only code built with Peal's postlinker can be loaded by Peal.
Peal does not provide support for ELF shared libraries.
Peal uses the stack space provided by PceNativeCall(), which is only 4 KB by default. There are ways to increase the ARM stack size, but Peal does not use any of them.

See the README for more details. The download package includes a complete example program.

Build the peal-postlink program in the postlink/ directory:
cd postlink; make
Write ARM code that uses global data or function pointers. ARM functions intended to be called by m68k code may take a single parameter. ARM functions that need to call back into m68k code should use the variables gEmulStateP and gCall68KFuncP from arm/pealstub.h.
unsigned long MyArmFunction(void *arg) { ... }
Write m68k code that uses the API in m68k/peal.h to load ARM code and call ARM functions:
PealModule m = PealLoadFromResources('armc', 1000); void *address = PealLookupSymbol(m, "MyArmFunction"); unsigned long result = PealCall(m, address, myArg); PealUnload(m);
Compile m68k/peal.c along with other m68k code.
Add -fPIC when compiling to compile all ARM code as position-independent:
arm-palmos-gcc -fPIC ...
Compile arm/pealstub.c along with other ARM code.
Add --emit-relocs when linking ARM code to preserve relocation information:
arm-palmos-ld --emit-relocs ...
or arm-palmos-gcc -Wl,--emit-relocs ...
Run the Peal postlinker to generate ARM code resources:
peal-postlink -s 1000 -t armc -o postlinked-rsrcs.ro linked-binary.bin
Add the resources generated by peal-postlink to your Palm program as usual.

If you don't like Peal, there are several other tools that help provide a more full-featured ARM environment on Palm OS: