This is a minor, if not trivial, "documentation" bug for make menuconfig. If you run "make menuconfig" to build a kernel and go to Processor Type And Features/High Memory Support, and read the help page for the "off" option, you will see this advice: "If you are compiling a kernel which will never run on a machine with more than 1 Gigabyte total physical RAM, answer "off" here...". This wrongly suggests that kernels for machines with exactly 1G of RAM should be compiled withouth high memory support. I suggests rewriting this help page to make it more precise. (As far as I can see from my dmesg output, the kernel can see only up to 896MB of RAM in low memory area). Reproducible: Always Steps to Reproduce: 1. make menuconfig 2. follow built-in documentation to configure high memory support 3. Actual Results: I was sure I configured the kernel to use all of my RAM, but in fact it used only part of it. Expected Results: Documentation for the kernel configuration should be corerect, not misleading. Portage 2.0.51.19 (default-linux/x86/2004.3, gcc-3.3.5, glibc-2.3.4.20040808-r1, 2.6.10-gentoo-r6 i686) ================================================================= System uname: 2.6.10-gentoo-r6 i686 AMD Athlon(tm) XP 2500+ Gentoo Base System version 1.4.16 Python: dev-lang/python-2.3.4-r1 [2.3.4 (#1, Feb 22 2005, 11:56:00)] ccache version 2.3 [enabled] dev-lang/python: 2.3.4-r1 sys-devel/autoconf: 2.13, 2.59-r6 sys-devel/automake: 1.5, 1.6.3, 1.4_p6, 1.8.5-r3, 1.9.4, 1.7.9-r1 sys-devel/binutils: 2.15.92.0.2-r1 sys-devel/libtool: 1.5.10-r4 virtual/os-headers: 2.4.22-r1 ACCEPT_KEYWORDS="x86" AUTOCLEAN="yes" CFLAGS="-O2 -march=athlon-xp -pipe" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3.3/env /usr/kde/3.3/share/config /usr/kde/3.3/shutdown /usr/kde/3/share/config /usr/lib/X11/xkb /usr/lib/mozilla/defaults/pref /usr/share/config /usr/share/texmf/dvipdfm/config/ /usr/share/texmf/dvips/config/ /usr/share/texmf/tex/generic/config/ /usr/share/texmf/tex/platex/config/ /usr/share/texmf/xdvi/ /var/qmail/control" CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/env.d" CXXFLAGS="-O2 -march=athlon-xp -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="CCACHE autoaddcvs autoconfig ccache distlocks sandbox sfperms" GENTOO_MIRRORS="ftp://linux.rz.ruhr-uni-bohum.de/gentoo-mirror/ ftp://ftp.wh2.tu-dresden.de/pub/mirrors/gentoo http://gentoo.zie.pg.gda.pl" LANG="pl_PL" LC_ALL="pl_PL" MAKEOPTS="-j2" PKGDIR="/usr/portage/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="x86 3dnow X alsa apm arts avi berkdb bitmap-fonts cdr crypt cups curl doc dvd emboss encode esd fam fbcon font-server foomaticdb fortran gdbm gif gmp gnome gpm gstreamer gtk gtk2 imagemagic imagemagick imlib ipv6 jpeg kde libg++ libwww mad mikmod mime mmx motif mozilla mp3 mpeg ncurses nls oggvorbis opengl oss pam pdflib perl png python qt quicktime readline sdl spell sse ssl svga tcltk tcpd tetex tidy tiff truetype truetype-fonts type1-fonts usb wxwindows xml2 xmms xv zlib" Unset: ASFLAGS, CBUILD, CTARGET, LDFLAGS, PORTDIR_OVERLAY
Please ask about this on the linux-kernel mailing list, it's an upstream issue, not a gentoo one.