As the original proposer, I say, Hear hear. The main reasons to choose that particular scheme were: - producers that use type sections must already have an MD5 implementation; - Visual Studio debugger integration uses it. But a more flexible scheme allowing other schemes would be a Good Thing. --paulr
> -----Original Message----- > From: dwarf-discuss-boun...@lists.dwarfstd.org [mailto:dwarf-discuss- > boun...@lists.dwarfstd.org] On Behalf Of Eric Christopher > Sent: Monday, March 31, 2014 3:57 PM > To: Mark Wielaard > Cc: DWARF > Subject: Re: [Dwarf-Discuss] Add file attributes to debug-line file > table (proposal 130701.1) > > FWIW I fully agree with this line of reasoning. I was going to propose > it as well (though not as comperhensively) since we may decide that we > want to use something other than "the low 64-bits of an md5 hash" to > represent the file. Speaking of which, the particular hash and such > should be explicitly changeable in the header. > > -eric > > On Tue, Mar 18, 2014 at 7:33 AM, Mark Wielaard <m...@redhat.com> 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 > _______________________________________________ > Dwarf-Discuss mailing list > Dwarf-Discuss@lists.dwarfstd.org > http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
