Jeremy's Weblog

About a month ago, I installed Gentoo on the new-to-me Acer Aspire1. Installation went like anything else, it is just a normal x86 host after all. I don’t have everything on it working, because I don’t care. If you are looking for additional resources on getting the extras working, you may want to look here or here.

The exciting part, that I got working and am ready to announce publicly, is my new atom-x86 binpkg repo. What makes this repo different than the binpkgs located on tinderbox.dev.gentoo.org/default-linux is that this repo has CFLAGS specific to the Intel Atom processor. I identified the compiler flags by using the following gcc command: gcc -Q --help=target -march=native and set the following -march=prescott -mtune=generic -msahf. On my linode (review) host, I have a chroot that builds all new packages in my world file once a day which comes from the aspire1. In this manor, I am able to always have binary packages available to me whenever I update my aspire1. Now, I have all the benefits of a source distro and the speed of a binary distro.

If you would like to use this repo, set PORTAGE_BINHOST in /etc/make.conf and add ‘getbinpkg’ to FEATURES (or use the emerge options directly). Be advised, that thought this works for me, I make no guarantees for you.

PORTAGE_BINHOST="http://tinderbox.jolexa.net/atom-x86/"
FEATURES="${FEATURES} getbinpkg"

I also have an html view of the packages available.

The problem:

$ dmesg |grep mtrr
mtrr: no more MTRRs available

I found on my ‘new-to-me’ AA1 that MTRR handling in the BIOS was messed up. Thanks to this bug report I figured out that I should compile the kernel with MTRR sanitizer enabled. That is:

$ zgrep -i MTRR /proc/config.gz
CONFIG_MTRR=y
CONFIG_MTRR_SANITIZER=y
CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT=1
CONFIG_MTRR_SANITIZER_SPARE_REG_NR_DEFAULT=1

And output of /proc/mtrr is as follows. Before and after.

$ cat /proc/mtrr
reg00: base=0x0fffe0000 ( 4095MB), size=  128KB, count=1: write-protect
reg01: base=0x0fffc0000 ( 4095MB), size=  128KB, count=1: uncachable
reg02: base=0x000000000 (    0MB), size=  512MB, count=1: write-back
reg03: base=0x020000000 (  512MB), size=  512MB, count=1: write-back
reg04: base=0x03f800000 ( 1016MB), size=    8MB, count=1: uncachable
reg05: base=0x03f600000 ( 1014MB), size=    2MB, count=1: uncachable
reg06: base=0x03f500000 ( 1013MB), size=    1MB, count=1: uncachable
reg07: base=0x000000000 (    0MB), size=  128KB, count=1: uncachable
after kernel modification:
reg00: base=0x000000000 (    0MB), size= 1024MB, count=1: write-back
reg01: base=0x03f500000 ( 1013MB), size=    1MB, count=1: uncachable
reg02: base=0x03f600000 ( 1014MB), size=    2MB, count=1: uncachable
reg03: base=0x03f800000 ( 1016MB), size=    8MB, count=1: uncachable
reg04: base=0x040000000 ( 1024MB), size=  256MB, count=1: write-combining

This is needed for decent video playback with the on-board Intel 945 video.