Re: [PATCH 1/5] kbuild: thin archives final link close --whole-archives option

[Nicholas Piggin <npiggin@gmail.com>]

On Wed, 21 Jun 2017 22:52:25 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Wed, Jun 21, 2017 at 1:32 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Wed, Jun 21, 2017 at 1:10 PM, Nicholas Piggin <npiggin@gmail.com> wrote:  
> >> On Wed, 21 Jun 2017 12:49:10 +0200
> >> Arnd Bergmann <arnd@arndb.de> wrote:
> >>  
> >>> On Wed, Jun 21, 2017 at 12:38 PM, Nicholas Piggin <npiggin@gmail.com> wrote:  
> >>> > On Wed, 21 Jun 2017 12:21:16 +0200
> >>> > Arnd Bergmann <arnd@arndb.de> wrote:
> >>> >  
> >>>
> >>> I'm building on top of yesterday's linux-next at the moment,
> >>> with a number of my own patches applied
> >>>  
> >>> > I can take a look at ARM and try to get it at least to parity with
> >>> > incremental link. Any particular config options required?  
> >>>
> >>> This is the patch I am testing with:
> >>>
> >>> https://pastebin.com/HQuhCEmK
> >>> I have not looked at that in a while, no idea if it works, or
> >>> if it has known problems.
> >>>
> >>> I last posted the patch in March for discussion:
> >>>
> >>> https://patchwork.kernel.org/patch/9626207/  
> >>
> >> Well I just mean the stuff now in kbuild/thin-ac, not the LD_DCDE.
> >> Just want to try getting thin archives up to a point where there are
> >> no serious regressions first.  
> >
> > For my build testing, I have now reverted most of my patch and only
> > left the 'select THIN_ARCHIVES'. I'll let you know if I run into problems.  
> 
> I just got one build failure on a randconfig build with THIN_ARCHIVES
> but without LD_DCDE:
> 
> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-ld: section .data VMA
> [0000000000808000,000000000096cc7f] overlaps section .text VMA
> [0000000000080080,00000000008a8427]
> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-ld: section .rodata VMA
> [00000000008a9000,0000000000ea216f] overlaps section .data VMA
> [0000000000808000,000000000096cc7f]
> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-ld: section .bss VMA
> [000000000096cd00,000000000157896f] overlaps section .rodata VMA
> [00000000008a9000,0000000000ea216f]
> /home/arnd/cross-gcc/bin/arm-linux-gnueabi-ld: section __param VMA
> [0000000000ea2170,0000000000ea5257] overlaps section .bss VMA
> [000000000096cd00,000000000157896f]
> 
> haven't spent any time analyzing it further, maybe you can see right
> away what caused this. If not, you could try the .config file at
> https://pastebin.com/raw/YTZKH9Xe

It's due to vmlinux-xip.lds.S explicitly putting sections inside each
other

        . = PAGE_OFFSET + TEXT_OFFSET;

Same config fails without thin archives for me.

If XIP can't place these dynamically, at least you should use an
ASSERT() linker script function if sizes overlap. E.g.,

    ASSERT(. <= PAGE_OFFSET + TEXT_OFFSET, "kernel too big");
    . = PAGE_OFFSET + TEXT_OFFSET;