On 06/24/2013 12:58 PM, Jakub Jelinek wrote: > On most targets, .debug_* sections are placed at address 0, so absolute > relocations are the same as relocations relative to the start of the > section. > [snipped] > > So, either .debug_* sections are placed at address 0 and then absolute > relocations will do the trick, or you need some kind of section relative > relocation (e.g. ia64 has it I think). This isn't specific just to > .debug_frame, e.g. DW_FORM_strp/DW_FORM_sec_offset encoded values in > .debug_info > or .debug_abbrev offsets in .debug_info CU header, DW_OP_call_ref arguments, > .debug_aranges/.debug_pubtypes/.debug_pubnames offsets to .debug_info all > have these requirements. > > Jakub
Aha, I see what's happening. For historical reasons, ARC Linux kernel stack unwinder relies on .debug_frame (vs. .eh_frame) for stack unwinding. Being non allocatable it would default to address zero hence the orig absolute relocations would work for most ports. However in our case we force it allocatable in kernel builds and thus it is relocated to 0x8abcdefg, thus the usage of absolute relocations ends up generating the invalid reference. Thus it seems we do need the special section relative reference. Thanks a bunch for clarifying. --Vineet
