tar backup restore

identify and mount directories/devices for backup sources and targets, i.e.
-- backup, which directory
-- backup, to which file, located where

tar - tape archiver
http://gnu.org/software/tar/manual
$ tar --help
some useful options
$ man tar
-c, --create
create a new archive

-t, --list
list the contents of an archive

-x, --extract, --get
extract files from an archive

-a, --auto-compress
use archive suffix to determine the compression program

-f, --file=ARCHIVE
use  archive file or device ARCHIVE

--numeric-owner
always use numbers for user/group names

--owner=NAME
Force NAME as owner for added files.

--one-file-system 
stay in local file system when creating archive

-p, --preserve-permissions, --same-permissions
extract information about file permissions (default for superuser)

--show-defaults
show tar defaults

-v, --verbose
verbosely list files processed

--xattrs
enable extended attributes support

backup
descend into directory, and tar current directory avoiding absolute pathname risks
$ cd {backup-directory}
$ sudo tar --one-file-system --numeric-owner --xattrs -cvapf /mnt/backup/{backup-filename}.tar.xz .

restore
descend into target directory, and untar
$ cd {target-directory}
$ sudo tar --one-file-system --numeric-owner --xattrs -xvapf /mnt/backup/{backup-filename}.tar.xz

combine tar with netcat to backup/restore across the network, significantly more efficient as the same system is not reading/writing at the same time, unless you are on a slow network.

gentoo kernel compile

I seem to be doing this so often that I need a ready reference. So here's a post :)

This sound device does not have any controls

I have no sound, on my recent gentoo install.

LXQT Mixer wouldn't open. I don't even get any error/warning messages. This is not good.

So I try alsamixer.

$ alsamixer
...
This sound device does not have any controls.

gentoo install x86 btrfs

this as a quick start guide to the much longer and more comprehensive gentoo handbook. but please understand what i have done, and not blindly copy. you should definitely read the gentoo install handbook a few times before even attempting an install.

gentoo first attempt

i finally decided to jump in, and created another btrfs partition for gentoo with two subvolumes. with btrfs i don't have anything on the root subvolume.

i really didn't expect an install to drag on for so long. i don't like to give up part-way, unless i feel it is a lost investment.. and i was losing it! i would have, but for some kindly folks on the gentoo forum. the gentoo forum is one of the most responsive and helpful forums i have been in.

multiboot btrfs subvolumes

this idea has been knocking around in my head for a while. i want to document it, while it is still there and to flush it out later..

i usually multiboot, and have several operating systems on the same disk. my currently laptop has about dozen+ partitions. each os is fully contained within a partition, including the bootloader on pbr. mbr is clean.

debian to gentoo

as debian builds more & more complexity/layers obscuring internals from users, i get more & more disillusioned by the current crop of debian decision-makers. jessie, the current debian stable seems no longer stable, and an unstable init at it's core.

wheezy is/was the last stable version gone oldstable now. oldstable is expected to be even more stable than stable. but recent updates have littered wheezy with systemd and ubuntu garbage including upstart. even oldstable has had more than a few days downtime recently, due to buggy updates. sad debian :(

bios acpi dsdt

bios: basic input/output system
acpi: advanced configuration power interface
dsdt: differentiated system description table
wheezy32: debian wheezy 32bit
arch32: arch 32bit

toshiba bios seem to be one of the most notorious and worst broken. do not choose toshiba for anything but windows, and even with that be careful. dodgy bios implementations are like broken foundations to build your home, if you want to live there yourself!

identify

so how do you identify, if your bios is broken/buggy? check kernel logs:
$ dmesg -l err
toshiba_acpi: Error reading LCD brightness
indicates direction of problems. this error points towards a buggy implementation of acpi by toshiba.

$ dmesg | grep DSDT
ACPI: DSDT 0x00000000B7CEF000 095BA (v01 TOSINV TOSINV00 00000001 MSFT 01000013)
TOSHIBA Satellite detected - force copy of DSDT to local memory
ACPI: Forced DSDT copy: length 0x095BA copied locally, original unmapped
ACPI: EC: Look up EC in DSDT
indicates that bios data is (used as original, forced) not overidden.
msft indicates that toshiba bios is specific to microsoft, particular to a windows version.
poor strategy, unless they were paid-off by microsoft.

confirm

how do you confirm whether bios provided data is usable? decompile & recompile.
a successful recompile, no errors/warnings indicates a good bios! and this has nothing to do with any operating system.

we need iasl, for this purpose.

$ apt-cache show iasl
Description: Intel ASL compiler/decompiler
 iASL compiles ASL (ACPI Source Language) into AML (ACPI Machine
 Language). This AML is suitable for inclusion as a DSDT in system
 firmware. It also can disassemble AML, for debugging purposes.
Homepage: http://acpica.org
# apt-get install iasl
$ iasl -h

$ cd /tmp
$ sudo cat /sys/firmware/acpi/tables/DSDT >dsdt.dat
$ iasl -d dsdt.dat
$ iasl -tc dsdt.dsl
the first command reads the dsdt data. do it as root.
the second command decompiles this .dat into .dsl
the third command attempts to compile, thereby generating the errors/warnings we are looking for.

i see this on wheezy32
$ iasl -tc dsdt.dsl
Intel ACPI Component Architecture
ASL Optimizing Compiler version 20100528 [Jul  2 2010]
Copyright (c) 2000 - 2010 Intel Corporation
Supports ACPI Specification Revision 4.0a

dsdt.dsl  3401:                     0x00000000,         // Length
Error    4122 -                              ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl  3408:                     0x00000000,         // Length
Error    4122 -                              ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl  7148:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7165:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7214:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7231:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7275:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7489:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7506:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7523:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7540:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  7557:                         Name (_PLD, Buffer (0x10)
Error    4080 -          Invalid object type for reserved name ^  (found BUFFER, requires Package)

dsdt.dsl  8873:                     Method (_GTM, 0, NotSerialized)
Warning  1088 -                                ^ Not all control paths return a value (_GTM)

dsdt.dsl  8873:                     Method (_GTM, 0, NotSerialized)
Warning  1081 -                                ^ Reserved method must return a value (Buffer required for _GTM)

dsdt.dsl  9033:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9033:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9101:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9101:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9174:                     Method (_GTM, 0, NotSerialized)
Warning  1088 -                                ^ Not all control paths return a value (_GTM)

dsdt.dsl  9174:                     Method (_GTM, 0, NotSerialized)
Warning  1081 -                                ^ Reserved method must return a value (Buffer required for _GTM)

dsdt.dsl  9334:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9334:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9402:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9402:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9507:                     Method (_GTM, 0, NotSerialized)
Warning  1088 -                                ^ Not all control paths return a value (_GTM)

dsdt.dsl  9507:                     Method (_GTM, 0, NotSerialized)
Warning  1081 -                                ^ Reserved method must return a value (Buffer required for _GTM)

dsdt.dsl  9667:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9667:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9735:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9735:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl  9808:                     Method (_GTM, 0, NotSerialized)
Warning  1088 -                                ^ Not all control paths return a value (_GTM)

dsdt.dsl  9808:                     Method (_GTM, 0, NotSerialized)
Warning  1081 -                                ^ Reserved method must return a value (Buffer required for _GTM)

dsdt.dsl  9968:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl  9968:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

dsdt.dsl 10036:                         Method (_GTF, 0, NotSerialized)
Warning  1088 -                                    ^ Not all control paths return a value (_GTF)

dsdt.dsl 10036:                         Method (_GTF, 0, NotSerialized)
Warning  1081 -                                    ^ Reserved method must return a value (Buffer required for _GTF)

ASL Input:  dsdt.dsl - 10111 lines, 370896 bytes, 4450 keywords
Compilation complete. 12 Errors, 24 Warnings, 0 Remarks, 37 Optimizations

12 errors, 24 warnings, i.e. not good!
i get the same results on arch32 too.. so don't go blaming wheezy32!

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