Difficulty with armv6 to v7 transition.

[Ian Lepore]

On Sat, 2017-10-14 at 08:28 +0200, Michal Meloun wrote:
> 
> On 14.10.2017 7:47, bob prohaska wrote:
> > 
> > Hi Michal,
> > 
> > On Sat, Oct 14, 2017 at 06:28:13AM +0200, Michal Meloun wrote:
> > > 
> > > Bob,
> > > can you please try this?
> > > setenv MACHINE_ARCH armv7; make buildworld TARGET=arm TARGET_ARCH=armv7
> > > 
> > I _believe_ I did try that, with no success,  but the scrollback buffer 
> > isn't long enough to let me verify it. 
> > 
> > Right now the machine is running buildworld, using 
> > BUILD_ARCH!= echo armv7
> > in /usr/src/Makefile.inc1 to set BUILD_ARCH.  If the
> > buildworld fails I'll try setenv, just to verify. Should know
> > late Saturday or early Sunday.
> > A more immediate puzzle is how to test whether the buildworld command
> > produced an armv7 userland, or something else, before running installworld.
> > I'd hate to trash the system _again_. Running clang -v ought to give a 
> > good hint, if I can find the executable. Is there a better test? 
> > 
> For not-installed world executable you can dump ABI version encoded in
> .note.tag section:
> ' objdump -s -j .note.tag  //bin/sh'
> 
> the right binary have something like this:
> -----------------------------------------------------
> /bin/sh:     file format elf32-littlearm
> 
> Contents of section .note.tag:
>  814c 08000000 04000000 01000000 46726565  ............Free
>  815c 42534400 b24f1200 08000000 04000000  BSD..O..........
>  816c 02000000 46726565 42534400 00000000  ....FreeBSD.....
>  817c 08000000 06000000 03000000 46726565  ............Free
>  818c 42534400 61726d76 37000000           BSD.armv7...
> -------------------------------------------------------
> where ' FreeBSD.armv7' is ABI version.
> 
> For installed world, the next method is 'make -V MACHINE_ARCH -f/dev/null'
> And for kernel, 'sysctl kern.supported_archs' and 'sysctl 
> hw.machine_arch' shoul return armv7
> 
> 

You can also get some info formatted nicely with readelf -A:

root at wand:~ # readelf -A /sbin/init
Attribute Section: aeabi
File Attributes
  Tag_CPU_arch: ARM v7
  Tag_CPU_arch_profile: Application Profile
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: 32-bit Thumb
  Tag_FP_arch: VFPv3
  Tag_Advanced_SIMD_arch: NEONv1
  Tag_ABI_PCS_GOT_use: direct
  Tag_ABI_PCS_wchar_t: wchar_t size 4
  Tag_ABI_FP_denormal: Sign Only
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte align
  Tag_ABI_align_preserved: 8-byte align
  Tag_ABI_enum_size: 32-bit
  Tag_ABI_VFP_args: AAPCS (VFP variant)
  Tag_ABI_optimization_goals: Speed
  Tag_ABI_FP_16bit_format: IEEE 754
  Tag_conformance: 2.09

When doing it to check before installworld, be sure to check the new
one in $OBJDIRPREFIX/arm.armv7/<path>/src/sbin/init/init

-- Ian