やらかしの原因

https://wiki.gentoo.org/wiki/Handbook:AMD64/Installation/Disks/ja#スワップパーティションを有効にする
↑こちらの手順を見落していたがために陥った問題でした。

「パーティションを切るのは何度もやってるし、別にガイド見なくてもよゆーでしょう」
👉「うわああああ▂▅▇█▓▒░(’ω’)░▒▓█▇▅▂」

以下のようなバグレポートを書いていました

dev-libs/boost-1.71.0 fails install phase on Chroot Environment with Minimal-install CD on VirtualBox

Problem

To install dev-libs/boost-1.71.0, I had to apply the workaround below on a chroot environment with minimal-install CD (install-amd64-minimal-20191211T214502Z.iso) on VirtualBox.

But, there was no problem to install boost with multi-threading option like MAKEOPTS="-j5", on already installed Gentoo environment on VirtualBox.

Workaround

Set the value MAKEOPTS="-j1".

For example,

mkdir /etc/portage/env
echo 'MAKEOPTS="-j1"' > /etc/portage/env/singlecore.conf
echo "dev-libs/boost singlecore.conf" >> /etc/portage/package.env
emerge --ask dev-libs/boost

Host System's Infomation

$ screenfetch -n
esi@esi-pc
OS: Manjaro 18.1.4 Juhraya
Kernel: x86_64 Linux 5.4.2-1-MANJARO
Uptime: 1d 1h 12m
Packages: 1200
Shell: bash
Resolution: 1280x1024
DE: KDE 5.64.0 / Plasma 5.17.4
WM: KWin
GTK Theme: Breath [GTK2/3]
Icon Theme: maia
Font: Noto Sans Regular
Disk: 48G / 70G (72%)
CPU: AMD A10-4655M APU with Radeon HD Graphics @ 4x 2GHz
GPU: GeForce GT 710
RAM: 6125MiB / 15935MiB

Host System's Infomation is here, as "host_system_info.txt".
https://drive.google.com/open?id=1IyPKrAkq-FrYB5MBPigODRXJAToCln3i

uname -a > host_system_info.txt
screenfetch -n -N >> host_system_info.txt
sudo lshw >> host_system_info.txt

Hardware infomation

VirtualBox 6.0.14 r132055 with Extension Pack 6.0.14

4core x86_64 CPU / UEFI Mode / Serial ATA AHCI Mode

configuration file is here, as "Gentoo.vbox".
https://drive.google.com/open?id=1Km0VxUjOs26Lb-8N_8WnDBw4aAIF74mt

Error Logs (on chroot environment)

emerge--info_dev-libs_boost-1.71.0.txt
(emerge --info '=dev-libs/boost-1.71.0::gentoo' > emerge--info_dev-libs_boost-1.71.0.txt)
https://drive.google.com/open?id=1G-4qw9iiDWMdFEugvruI4P8qHZ9sGFEN

/var/tmp/portage/dev-libs/boost-1.71.0/temp/build.log as build.log_dev-libs_boost-1.71.0.txt
https://drive.google.com/open?id=1cRHe2tFtL3JyEekTxryMSrH9KxmludnL

Files for Comparison (on already installed Gentoo environment)

/usr/src/linux/.config as dot_config_noproblem.txt
https://drive.google.com/open?id=1HiD0h44GB-kW_fUlcDXwRpnNcBRwewid

emerge--info_dev-libs_boost-1.71.0_noproblem.txt
https://drive.google.com/open?id=1457-eBOI2sEfhw0WO6Jb7j8p6HazFDDH

I compared emerge--info_dev-libs_boost-1.71.0.txt and emerge--info_dev-libs_boost-1.71.0_noproblem.txt, and found that the lack of swap caused this problem.

提出前に気がついてよかった

/dev/sda2 に swap 領域を用意してある状態で、swapon /dev/sda2したうえでemerge dev-libs/boostしてみると無事ビルドが通りました。

MAKEOPTS="-j5" かつメモリ割り当て 2G では swapon しないと不正終了。MAKEOPTS="-j1" なら swap 領域無しでもビルドが通りました。

Gentoo のバグレポガイドはこちら

https://wiki.gentoo.org/wiki/Bugzilla/Bug_report_guide
https://wiki.gentoo.org/wiki/Bugzilla/Bug_report_guide/ja