On 07.03.2023 13:04, Juergen Gross wrote: > On 07.03.23 12:42, Jan Beulich wrote: >> On 07.03.2023 12:33, Juergen Gross wrote: >>> On 07.03.23 11:31, Jan Beulich wrote: >>>> On 07.03.2023 07:32, Juergen Gross wrote: >>>>> Using a rather oldish gcc (7.5) it was verified that code generation >>>>> doesn't really differ between CONFIG_DEBUG_INFO on or off without >>>>> CONFIG_DEBUG being set (only observed differences were slightly >>>>> different symbol addresses, verified via "objdump -d"). The old gcc >>>>> version selection was based on the assumption, that newer gcc won't >>>>> regress in this regard. >>>> >>>> This is good to know, but I'm still curious about the mentioned >>>> differences in symbol addresses: If code generation didn't change, what >>>> caused addresses to differ? Is that merely because individual functions >>>> or objects are emitted in different order by the compiler? (If so I'd >>>> be inclined to infer that comparing generated code must have been >>>> quite a bit of effort, as first of all you would have had to undo that >>>> re-ordering.) >>> >>> I did a simple diff of the two disassembly outputs and got only small >>> differences for %rip relative addresses (the differences were in the >>> range of +/- 32 bytes). >> >> That's still odd and hence imo wants understanding. Do you still have >> both binaries around? > > I have just regenerated the one with debug-info. It is a 4.17 build. > > I just found the at least one reason: xen_config_data has a different size > (obviously!) and this finally leads to an offset of 32 bytes for symbols > at higher addresses (with some items only differing by 8 bytes due to > alignment).
Thanks for checking - this kind of a delta is of course to be expected. Jan
