[Dwarf-Discuss] Proposal to reserve .debug_macro opcode 0xff

Michael Eager eager at eagerm.com
Tue Sep 30 17:06:12 PDT 2014


On 09/30/14 16:30, Petr Machata wrote:
> Hello,
>
> I'm working on support in elfutils for the .debug_macro proposal[1].
>
> The numerical values and semantics of DW_MACINFO_* opcodes are
> equivalent to their new-style DW_MACRO_* counterparts.  So a decoder
> could transparently read in .debug_macro instead of .debug_macinfo, and
> serve the opcodes found there to a client, without fear that they get
> misinterpreted.
>
> Were it not for DW_MACINFO_vendor_ext, 0xff.  This value, in new-style
> sections, is part of the vendor extension block, as DW_MACRO_hi_user.
> It could be allocated and emitted, and a client would misinterpret it as
> DW_MACINFO_vendor_ext, decode it, and make decisions based on this
> misinterpretation.
>
> I would therefore like to propose that the opcode 0xff is considered
> reserved, and DW_MACRO_hi_user is changed to 0xfe.
>
> Does this sound reasonable?  Should I file an issue for this?
>
> [1] http://www.dwarfstd.org/ShowIssue.php?issue=110722.1
>

Yes, please file a comment.


-- 
Michael Eager	 eager at eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077


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