OpenE2K Gentoo overlay

This overlay adds Elbrus 2000 architecture support on top of the existing Gentoo upstream repository.

To make it work, new profile and keyword are added.

• Through magic of symlinks, e2k profile is based on upstream Gentoo profiles.
• Keyword e2k is only added to the packages that are specifically patched to support Elbrus.
• As changes of getting this upstreamed are very slim due to proprietary compilers, packages that can be built as-is, are enabled through amd64 keyword, so we don't have to patch every ebuild from the upstream.
  • It's temporarily on my machine /etc/portage, but could be added in profile, if profiles support .accept_keywords. package.accept_keywords is landed into profile.
• The only patch is required for Gentoo portage tree is adding e2k to supported arches in eclass/toolchain-funcs.eclass:

diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
index 89da26b86..8f65033c1 100644
--- a/eclass/toolchain-funcs.eclass
+++ b/eclass/toolchain-funcs.eclass
@@ -783,6 +783,7 @@ tc-ninja_magic_to_arch() {
 		bfin*)		_tc_echo_kernel_alias blackfin bfin;;
 		c6x*)		echo c6x;;
 		cris*)		echo cris;;
+		e2k*)		echo e2k;;
 		frv*)		echo frv;;
 		hexagon*)	echo hexagon;;
 		hppa*)		_tc_echo_kernel_alias parisc hppa;;

Acknowledgments

Thanks to MCST and ALT Linux Team for their efforts and publishing patches for Elbrus support, as OpenE2K is based around ~90% of their work. Thanks to Gentoo team for creating such flexible distribution and package manager.

Current state

Supported profiles:

• default/linux/e2k/23.0
• default/linux/e2k/23.0/systemd

Supported CPUs (defined as ABI in the profile):

• Elbrus 4C
• Elbrus 8CB

Supported ABIs:

• ptr32
• ptr64
• ptr128

TODO:

• Fill out missing parts above. :)
• Get rid of hardcoded stuff
  • Add copyrights to ebuilds.
  • Move e2k keyword to ~e2k, as it's obviously not tested.
  • Remove all other keywords, so e2k specific packages won't get accidentally pulled on supported by upstream system.
• Build parts of lcc-libs that have source code published:
  • compiler-rt
  • libatomic
  • libgcc
  • libquadmath
  • libstdc++
• Build and publish stage3
• Moar e2k packages:
  • Add MCST and Unipro LLVM ports as separate packages
  • Add MCST Rust port
  • Add rtc (x86 binary translator) package, maybe neatly integrate as multilib, etc...
• Cross compiling support

Example make.conf

# Set CPU_MODEL to the processor you have.
# We follow the naming scheme of LCC compiler binary packages as the sole
# reason for this variable is to know which compiler binary we need to get
# - e4c for Elbrus-4C
# - e1c for Elbrus-1C+
# - e8c for Elbrus-8C
# - e8c2 for Elbrus-8CB
# - e2c3 for Elbrus-2C3
# - e16c for Elbrus-16C
CPU_MODEL="e4c"

# Be careful with -mtune flag, with it LCC will set "forward incompatible" flag
# in the ELF header preventing you from running compiled binaries on newer CPUs
#
# OpenE2K stage3 is built for Elbrus-4C by default, which you are supposed to
# recompile for your native ISA.
COMMON_FLAGS="-O3 -pipe"
CFLAGS="${COMMON_FLAGS}"
CXXFLAGS="${COMMON_FLAGS}"
FCFLAGS="${COMMON_FLAGS}"
FFLAGS="${COMMON_FLAGS}"

MAKEOPTS="-j17 -l17"
VIDEO_CARDS="radeonsi amdgpu"