Hi Mark -- I'll pass your comments on to the DWARF Committee.
On 03/18/14 07:33, Mark Wielaard wrote:
Hi, I was reading the suggestion for adding MD5 digests to the .debug_line program header. http://dwarfstd.org/ShowIssue.php?issue=130701.1 Adding more attributes of files seems like a good thing, but as specified this isn't extensible without changing the version number again and defining new formats. Would it be possible to make this a little more generic and vendor extensible? The .debug_macro proposal includes some language for defining extensibility that could possibly be used. http://dwarfstd.org/ShowIssue.php?issue=110722.1 So instead of a fixed file_entry_format (ubyte) field that just allows one attribute (group) to be defined we could change it to something like: file_attributes (ubyte) - Possibly zero, number of attributes added to each file in the file_names table. file_attribute_description (sequence of attribute descriptions) - Entries in this description describe which attributes and in what format those attributes are encoded for each file entry. It has file_attributes entries. Each entry consists of: - file_attribute (ubyte). One of DW_LNF_timestamp, DW_LNF_length, DW_LNF_MD5, ... - file_attribute_format. A uleb128 describing the number of arguments for the format followed a single byte describing the form of the argument. The allowed values are DW_FORM_data1, DW_FORM_data2, DW_FORM_data4, DW_FORM_data8, DW_FORM_sdata, DW_FORM_udata, DW_FORM_block, DW_FORM_block1, DW_FORM_block2, DW_FORM_block4, DW_FORM_flag, DW_FORM_string, DW_FORM_strp and DW_FORM_sec_offset. file_names (sequence of file entries) - Each entry consists of the following values: - A null-terminated string containing the full or relative path name of a source file. - An unsigned LEB128 number representing the directory index of a directory in the include_directories section. - For each file_attribute_format described in the file_attribute_description entries the value encoded in the format given by file_attribute_format. For example DW_LNF_timestamp and DW_LNF_length would have as format 1 DW_FORM_udata. DW_LNF_MD5 could by described by 2 DW_FORM_data8. That would allow extending the number of attributes in later DWARF versions or as vendor extensions and give consumers a way to skip over any unknown attributes. Would something like the above suggestion be useful? Then I can work it out a bit more. Did I miss any subtle corner cases? What is the status of the .debug_macro proposal (110722.1)? It would be good to match the descriptions of both extension mechanisms as much as possible. Thanks, Mark _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
-- Michael Eager ea...@eagercon.com 1960 Park Blvd., Palo Alto, CA 94306 650-325-8077 _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
