Using gcc binpkg on different profile

[salam]

I have 2 hosts, a fast bare metal and a slow VM. As this package takes ages to complete, I am thinking, if it is possible to build gcc(emerge -B) on the fast one and use it as a binary package on the slower. But they have different profiles.

Fast: [9] default/linux/amd64/23.0/no-multilib (stable) *
Slow: [13] default/linux/amd64/23.0/no-multilib/hardened/selinux (stable) *

CFLAGS are same on both:
COMMON_FLAGS="-O2 -pipe -march=x86-64 -mtune=intel"
CFLAGS="${COMMON_FLAGS}"
CXXFLAGS="${COMMON_FLAGS}"
FCFLAGS="${COMMON_FLAGS}"
FFLAGS="${COMMON_FLAGS}"
ABI_X86="64"

The only difference i see is the hardened use flag on gcc. So would using a binary on the slower host, made with USE="hardened" emerge -B gcc, work correctly, or is there something that prevents such a build?

[freke]

I'd expect it to work, but it might rebuild other stuff with hardened on your non-hardened machine if something else needs to be hardened to build hardened gcc?

I'd try an USE="hardened" emerge -pv sys-devel/gcc to see if it pulls in/wants other stuff to be built.

[NeddySeagoon]

salam,

The hardened profile turns on extra default gcc flags. They would be missing if you used the binary from the the fast machine.

You could run your own binhost builder in a chroot on the fast system, then install the binaries on the VM.
The chroot would be a copy of the VM.

[pietinger]

salam,

maybe you are interested in this wiki article:
https://wiki.gentoo.org/wiki/Hardened/Toolchain#Changes

[salam]

After digging out some additional info, i tried it the hard way - so first i compiled gcc on the non-hardened host:

Code: Select all

USE="hardened" emerge -av1B gcc

I then locally extracted the package to see what differs. So far, i worked only with a single binary - x86_64-pc-linux-gnu-gcc
Executed cmp -l -b on the original build, which was done on the hardened profile and this new build(non-hardened profile, but forced +hardened use flag). But I only found out that the whole difference is the order of flags passed to ./configure

I see the diff only in 2 places:

Code: Select all

  [ 2] .note.gnu.bu[...] NOTE             00000000000003d8  000003d8
       0000000000000024  0000000000000000   A       0     0     4

and

Code: Select all

  [18] .rodata           PROGBITS         00000000000f9000  000f9000
       00000000000b28f8  0000000000000000   A       0     0     32

The rodata diff is exactly the config flag order, which is quite readable even from cmp output
Other than that, the binaries look the same. Or am i searching a completely wrong place?