19march12

= 19 March 2012 LUG meeting notes =

We had an EUMETSAT GNU/Linux User group meeting on Monday-19-March-2012.

The turn out was small, and rather than a specific theme, we just chatted about GNU/Linux and hi-tech in general.

GRUB2 Boot Manager
We chatted briefly about Grub2, noting that both Fedora and Ubuntu use Grub2, and that openSUSE may move to Grub2 in the upcoming openSUSE-12.2 (if the current bugs in the alpha can be fixed). I noted that the current 'alpha' release of openSUSE-12.2 (known as milestone2) according to some accounts has a very very shaky and inadequate Grub2 setup, and more development/packaging work by SuSE-GmbH is needed for it to be included in a functional openSUSE-12.2 (release this summer).

While the legacy grub had a /boot/grub/menu.lst file, the newer Grub2 has a different arrangement for configuration files (as documented in a print out of a grub2 web page that I brought to the meeting). According to that page GRUB 2 places its files in three core locations (and I quote from that page) :


 * /boot/grub/grub.cfg - This is the main configuration file that replaces menu.lst. Unlike menu.lst, this file cannot be edited by hand!  I strongly advise against trying to tamper with this file, using chattr command or anything of the sort. Let it be.
 * /etc/grub.d/ - This new directory contains GRUB scripts. These scripts are building blocks from which the grub.cfg file is built. When the relevant GRUB command is executed, the scripts are read in a certain sequence and grub.cfg is created.
 * /etc/default/grub - This file contains the GRUB menu settings that are read by the GRUB scripts and written into grub.cfg. It is the customization part of the GRUB, similar to the old menu.lst, except the actual boot entries.
 * and after one edits /etc/default/grub and/or updates the scripts in /etc/grub.d, one still needs to run an application (called update-grub) for the update to the grub.cfg file to be made/applied.

(Post meeting note: Device naming has changed between GRUB and GRUB2. Partitions are numbered from 1 instead of 0 while drives are still numbered from 0, and prefixed with partition-table type). We chatted about the pros and cons of placing the legacy grub and Grub2 in the MBR and/or in a separate partition. Grub2 purported has advantages over legacy grub. One advantage noted is GRUB2 provides the ability to boot from GPT in both BIOS and UEFI based systems, while it was not so clear to us how well the legacy grub could handle such systems (if at all).

GPT (GUID Partition Table)
We chatted a bit about GUID Partition Table (GPT), which is a new style of partitioning which is part of the UEFI (Unified Extensible Firmware Interface) Specification, using a globally unique identifier for devices. [Unfortunately we struggled a bit during the meeting trying to recall the exact terminology]. GPT is purportedly different from the Master Boot Record (the more commonly used partitioning style) in various aspects and has advantages. For example using the older MBR limits the maximum addressable size of the disk to be 2TB. Any space beyond 2TB cannot be defined in a partition if MBR partitioning is used. But GPT can go beyond that 2TB limitation. Not mentioned in the meeting (but I noted later when reading up on the topic) was that GPT stores a backup header and partition table at the end of the disk that aids in recovery if the main copy is clobbered.

UEFI (Unified Extensible Firmware Interface)
We chatted about UEFI, which is the firmware that will eventually replace BIOS in commercial PCs. Again, we struggled to recall the exact terminology during the meeting. Many vendors have started adopting UEFI as their firmware. Linux officially supports both the UEFI and BIOS firmware. However Windows supports UEFI only with Vista (and Windows7 ? ) for x86_64, SP1 and later, and only with GPT partitioning. Apple supports EFI booting for Mac OS X. We were not clear if Grub2 was necessary to support UEFI or if it could be used with legacy Grub.

None of us had actually used GPT or UEFI, although it appears these configurations will become more common in the future.

AHCI (Advanced Host Controller Interface) settings in a PC's BIOS
We chatted a bit about AHCI, although during the meeting the 'exact' acronym slipped my mind. I noted I was thinking of changing my main PC (at home) Bios setting for the hard drive access (for my 1.5 TB sata hard drive) from 'IDE' to 'AHCI' over the Easter timeframe, and was likely going to re-install my legal copy of winXP and also a new version of openSUSE-12.1 with that AHCI setting. It was not clear to me if I could just change from 'IDE' to 'AHCI' without being forced to re-install/re-format. I noted I had read that AHCI is supported now by openSUSE GNU/Linux. Post Meeting note - I've read one can obtain drivers for AHCI for WinXP (although it is not supported 'out of the box'). According to a wiki article I read, in Linux systems if the AHCI driver is built as a module, rather than included in the kernel, it may not be loaded into the initrd (initial RAM disk) created when in legacy mode (as opposed to AHCI mode) and the workaround is to build a new initrd containing the AHCI module. Hence to avoid such complications, I plan to switch to AHCI only as part of my installation of openSUSE-12.1 (I am currently running openSUSE-11.4).

Linux Distributions in General
We chatted a bit about different GNU/Linux distributions, noting that Linux Mint (a Unbuntu/Debian based distribution) is becoming quite popular.

Android – Ice Cream Sandwich (version 4.0.3)
I noted I had updated the Android GNU/Linux on my Asus Transformer Tablet from Android-3.2.1 to Android-4.0.3. The Android-4.0.3 implementation on the 1st (and 2nd) generation Asus Transformer Tablets appears a bit buggy, with random crashes/reboots when the Tablet is in sleep mode. I typically see one per day with 4.0.3, and I did not notice the same with 3.2.1. Many in the Asus Transformer community are upset about this. I’ve been tracking this on the xda-developers forum.

Misc
We also chatted a bit about bittorrent, and proxy websites

Notes by Lee