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With my attempt to figure out why the PPC builds aren't working, I've spent a little more time working on improving the error reporting in forthstrap. Having had more of an insight as to how forthstrap works, I figured it might be useful to share my notes on how the process works.
Tracing through the code, I now realise why my first attempt at locating errors didn't work very well. It seems that forthstrap (kernel/bootstrap.c) actually has two different modes depending upon whether a base dictionary is supplied on the command line or not.
- If no base dictionary is supplied, then the input source files are compiled using the C implementation of the forth interpreter realised by the interpret_source() function.
- If a base dictionary is supplied, load the base dictionary from disk and invoke the initialize word in order to run the forth kernel.
From the Makefile it is possible to see that the first time forthstrap is invoked, no base dictionary is supplied and so a dictionary containing a basic Forth interpreter is built using the C interpreter implementation in kernel/bootstrap.c.
On subsequent calls to forthstrap, the previous dictionary is passed in as a base dictionary. forthstrap loads the dictionary and invokes the initialize word to run the Forth interpreter. The important part is the #ifdef...#endif section in kernel/forth.c for the "key" word. What this does is override the default I/O functions so that the contents of each input file passed on the command line are piped into the kernel one character at a time.
By adding a new switch to forthstrap and trapping the "emit" word in a similar way, it is possible to redirect the console output to a separate file for debugging purposes. Hence I've added a -c switch to forthstrap and altered the build system so that for a given base dictionary foo.dict, a new file call foo.dict-console.log is automatically generated which shows the Forth words being piped into the kernel.
With these changes in place, the ability to debug a broken build is considerably increased. Now when I try and build one of the broken PPC builds (in this case pearpc), I get the following in SVN trunk:
Configuring OpenBIOS on amd64 for cross-ppc Initializing build tree obj-ppc...ok. Creating target Makefile...ok. Creating config files...ok. Building OpenBIOS for ppc Building...error: make: Entering directory `/home/build/src/openbios/openbios-devel.pre/obj-ppc' GEN target/include/openbios-version.h GEN forth/version.fs HOSTCC host/kernel/bootstrap.o HOSTCC host/kernel/dict.o HOSTCC host/kernel/primitives.o HOSTCC host/kernel/stack.o HOSTCC forthstrap GEN bootstrap.dict GEN openbios.dict GEN openbios-pearpc.dict ../arch/ppc/pearpc/tree.fs:64: no such device. make: *** [openbios-pearpc.dict] Error 1 make: Leaving directory `/home/build/src/openbios/openbios-devel.pre/obj-ppc' make: *** [build] Error 1
Surely enough, at the end of line 63 in arch/ppc/pearpc/tree.fs we see the following:
" /pci" find-device
Hence it seems as if no /pci node is being created which is breaking the pearpc build. And just to confirm this, the last few lines of openbios-pearpc.dict-console.log look like this:
build@zeno:~/src/openbios/openbios-devel.pre$ tail -n 5 obj-ppc/openbios-pearpc.dict-console.log 0 > h# 88201 encode-int " cpu-version" property ok 0 > 0 encode-int " reg" property ok 0 > finish-device ok 0 > ok 0 > " /pci" find-device
Now I've got things to the point where the error reporting works well, I'll get back to finishing up my loader consolidation patch...