[lldb-dev] ELF file header e_machine number registration question

Matthew Gardiner mg11 at csr.com
Fri Jun 13 04:11:36 PDT 2014

Hi folks,

At some stage I'd like to submit to upstream lldb some changes to 
ArchSpec.h/.cpp and ELF.h which contain entries for some of CSR's 
Kalimba processors.

One concern of ours is the fact that the e_machine number our toolchain 
puts in our ELF files was not registered with the System V ABI. For 
historic reasons we chose a pseudo-random number 0x72ec (decimal 29420).

Is it permissible for me to continue to use this number, and submit into 
llvm/include/llvm/Support/ELF.h the following:

+ EM_KALIMBA = 29420 // Kalimba

Or is it the llvm/lldb practice that the machine architectures listed in 
the above file must be officially with the ABI people?

At CSR we have briefly discussed the idea and although we could 
retrospectively register our processors, we would then stop putting 
0x72ec in our ELFs, and that would break a lot of previously written tools.

Could somebody please clarify this point for me?

Matthew Gardiner

Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
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