modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Alexey.Brodkin@synopsys.com (Alexey Brodkin)]

Hi Daniel,

On Thu, 2016-09-22@15:37 -0700, Daniel Mentz wrote:
> On Thu, Sep 22, 2016 at 1:59 PM, Vineet Gupta
> <Vineet.Gupta1@synopsys.com> wrote:
> > 
> > Hi Daniel,
> > 
> > On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> > > 
> > > I confirmed that the .eh_frame section is present and that the
> > > .debug_frame section is absent. I also verified that the file size of
> > > the .ko files are small enough for our embedded platform and that
> > > unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> > > are also absent.
> > 
> > BTW it seems with my latest set of patches, modules still have .debug_*.
> > Can you double check if your tree still has the interim patch which added a linker
> > script for modules to strip out .debug_*
> > 
> > http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html
> 
> Hi Vineet,
> 
> Sorry, that was a misunderstanding. Buildroot routinely runs the strip
> command on .ko files before installing them on the target. I was only
> looking at the .ko files *after* running the strip command. No, the
> interim patch was not in my tree.

Well are you sure buildroot really touches modules in Linux kernel build folder?
Buildroot just runs a simple "make" command in "output/build/linux-x.y".

And only on installation step Buildroot strips binaries in "output/target" folder.
Moreover starting from that commit
https://git.buildroot.net/buildroot/commit/?id=10c4d27aef4dca01572cfc8146cbfd194a1a85e4
even on Linux installation step Buildroot reuses kernel's module stripping infrastructure
but again that happens only on target.

Just in case that's what I see when building MSDOSFS as module.

In build folder:
----------------------------->8-------------------------------
arc-linux-readelf -S build/linux-4.7.3/fs/fat/msdos.ko
There are 38 section headers, starting at offset 0x2a630:

Section Headers:
? [Nr] Name??????????????Type????????????Addr?????Off????Size???ES Flg Lk Inf Al
? [ 0]???????????????????NULL????????????00000000 000000 000000 00??????0???0??0
? [ 1] .note.gnu.build-i NOTE????????????00000000 000034 000024 00???A??0???0??4
? [ 2] .text?????????????PROGBITS????????00000000 000058 0013a8 00??AX??0???0??4
? [ 3] .rela.text????????RELA????????????00000000 01c774 000600 0c???I 35???2??4
? [ 4] .init.text????????PROGBITS????????00000000 001400 000010 00??AX??0???0??4
? [ 5] .rela.init.text???RELA????????????00000000 01cd74 000018 0c???I 35???4??4
? [ 6] .exit.text????????PROGBITS????????00000000 001410 000010 00??AX??0???0??4
? [ 7] .rela.exit.text???RELA????????????00000000 01cd8c 000018 0c???I 35???6??4
? [ 8] .rodata???????????PROGBITS????????00000000 001440 000100 00???A??0???0 64
? [ 9] .rela.rodata??????RELA????????????00000000 01cda4 000078 0c???I 35???8??4
? [10] .modinfo??????????PROGBITS????????00000000 001540 000090 00???A??0???0??4
? [11] .rodata.str1.4????PROGBITS????????00000000 0015d0 000030 01 AMS??0???0??4
? [12] .data?????????????PROGBITS????????00000000 001600 00002c 00??WA??0???0??4
? [13] .rela.data????????RELA????????????00000000 01ce1c 000030 0c???I 35??12??4
? [14] .gnu.linkonce.thi PROGBITS????????00000000 001640 000140 00??WA??0???0 64
? [15] .rela.gnu.linkonc RELA????????????00000000 01ce4c 00000c 0c???I 35??14??4
? [16] .tdata????????????PROGBITS????????00000000 001780 000000 00 WAT??0???0??1
? [17] .tbss?????????????NOBITS??????????00000000 001780 000000 00 WAT??0???0??1
? [18] .bss??????????????NOBITS??????????00000000 001780 000000 00??WA??0???0??1
? [19] .comment??????????PROGBITS????????00000000 001780 000078 01??MS??0???0??1
? [20] .note.GNU-stack???PROGBITS????????00000000 0017f8 000000 00??????0???0??1
? [21] .debug_aranges????PROGBITS????????00000000 0017f8 000048 00??????0???0??1
? [22] .rela.debug_arang RELA????????????00000000 01ce58 00003c 0c???I 35??21??4
? [23] .debug_info???????PROGBITS????????00000000 001840 00eaa9 00??????0???0??1
? [24] .rela.debug_info??RELA????????????00000000 01ce94 00a53c 0c???I 35??23??4
? [25] .debug_abbrev?????PROGBITS????????00000000 0102e9 0008b3 00??????0???0??1
? [26] .debug_line???????PROGBITS????????00000000 010b9c 001d4d 00??????0???0??1
? [27] .rela.debug_line??RELA????????????00000000 0273d0 001818 0c???I 35??26??4
? [28] .debug_frame??????PROGBITS????????00000000 0128ec 0002d8 00??????0???0??4
? [29] .rela.debug_frame RELA????????????00000000 028be8 000168 0c???I 35??28??4
? [30] .debug_str????????PROGBITS????????00000000 012bc4 008485 01??MS??0???0??1
? [31] .debug_loc????????PROGBITS????????00000000 01b049 000b49 00??????0???0??1
? [32] .rela.debug_loc???RELA????????????00000000 028d50 001308 0c???I 35??31??4
? [33] .debug_ranges?????PROGBITS????????00000000 01bb92 0001f8 00??????0???0??1
? [34] .rela.debug_range RELA????????????00000000 02a058 000480 0c???I 35??33??4
? [35] .symtab???????????SYMTAB??????????00000000 01bd8c 0005e0 10?????36??53??4
? [36] .strtab???????????STRTAB??????????00000000 01c36c 000407 00??????0???0??1
? [37] .shstrtab?????????STRTAB??????????00000000 02a4d8 000157 00??????0???0??1
Key to Flags:
? W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
? L (link order), O (extra OS processing required), G (group), T (TLS),
? C (compressed), x (unknown), o (OS specific), E (exclude),
? p (processor specific)
----------------------------->8-------------------------------

On target:
----------------------------->8-------------------------------
arc-linux-readelf -S target/lib/modules/4.7.3/kernel/fs/fat/msdos.ko?
There are 24 section headers, starting at offset 0x28e0:

Section Headers:
? [Nr] Name??????????????Type????????????Addr?????Off????Size???ES Flg Lk Inf Al
? [ 0]???????????????????NULL????????????00000000 000000 000000 00??????0???0??0
? [ 1] .note.gnu.build-i NOTE????????????00000000 000034 000024 00???A??0???0??4
? [ 2] .text?????????????PROGBITS????????00000000 000058 0013a8 00??AX??0???0??4
? [ 3] .rela.text????????RELA????????????00000000 002128 000600 0c???I 21???2??4
? [ 4] .init.text????????PROGBITS????????00000000 001400 000010 00??AX??0???0??4
? [ 5] .rela.init.text???RELA????????????00000000 002728 000018 0c???I 21???4??4
? [ 6] .exit.text????????PROGBITS????????00000000 001410 000010 00??AX??0???0??4
? [ 7] .rela.exit.text???RELA????????????00000000 002740 000018 0c???I 21???6??4
? [ 8] .rodata???????????PROGBITS????????00000000 001440 000100 00???A??0???0 64
? [ 9] .rela.rodata??????RELA????????????00000000 002758 000078 0c???I 21???8??4
? [10] .modinfo??????????PROGBITS????????00000000 001540 000090 00???A??0???0??4
? [11] .rodata.str1.4????PROGBITS????????00000000 0015d0 000030 01 AMS??0???0??4
? [12] .data?????????????PROGBITS????????00000000 001600 00002c 00??WA??0???0??4
? [13] .rela.data????????RELA????????????00000000 0027d0 000030 0c???I 21??12??4
? [14] .gnu.linkonce.thi PROGBITS????????00000000 001640 000140 00??WA??0???0 64
? [15] .rela.gnu.linkonc RELA????????????00000000 002800 00000c 0c???I 21??14??4
? [16] .tdata????????????PROGBITS????????00000000 001780 000000 00 WAT??0???0??1
? [17] .tbss?????????????NOBITS??????????00000000 001780 000000 00 WAT??0???0??1
? [18] .bss??????????????NOBITS??????????00000000 001780 000000 00??WA??0???0??1
? [19] .comment??????????PROGBITS????????00000000 001780 000078 01??MS??0???0??1
? [20] .note.GNU-stack???PROGBITS????????00000000 0017f8 000000 00??????0???0??1
? [21] .symtab???????????SYMTAB??????????00000000 0017f8 000540 10?????22??43??4
? [22] .strtab???????????STRTAB??????????00000000 001d38 0003ed 00??????0???0??1
? [23] .shstrtab?????????STRTAB??????????00000000 00280c 0000d3 00??????0???0??1
Key to Flags:
? W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
? L (link order), O (extra OS processing required), G (group), T (TLS),
? C (compressed), x (unknown), o (OS specific), E (exclude),
? p (processor specific)
----------------------------->8-------------------------------

-Alexey