mkimage-profiles/sub.in/stage1
Michael Shigorin fe58c46ead stage2: tunable squashfs compression
The existing implementation would handle kernel differences
just fine but a bit too automatically: if it sees xz support,
that's what will end up being used (and if there's -Xbcj binary
compression filter available for the target platform, it will
be applied unequivocally either).

It's perfectly suitabe for getting fine-tuned release images
but is also a bit too resource-consuming while developing the
image configuration which has no business with its compression.

The one and only knob is SQUASHFS (see doc/variables.txt);
to give an idea of the differences, here are some numbers
for a mostly-binary (43% as per 99-elf-stats) webkiosk livecd
and a rather less so (18%) flightgear one on a dual quad-core
X5570 node (each mksquashfs run used up all the cores):

SQUASHFS | live-webkiosk.iso | live-flightgear.iso
---------+-------------------+---------------------
fast     | 3:30 / 130M       | 5:11 / 852M
normal * | 3:37 / 100M       | 5:35 / 688M
tight    | 3:50 / 98M        | 6:47 / 683M

Thus if the knob isn't fiddled with, the defaults will allow
for a reasonably fast build of a pretty slim image; if one is
building a release or if a particular image is very sensitive
being close to the media capacity then just add SQUASHFS=tight
and see it a percent or two down on size.

Please note that lzo/gzip-compressed images are also quicker
to uncompress thus further helping with test iterations.

Thanks to led@ and glebfm@ for helpful hints and questions.
2012-04-09 22:03:29 +03:00
..
files features' day 2011-11-03 20:39:01 +02:00
scripts.d moved stage1 scripts into feature.in/installer 2011-11-04 16:15:29 +02:00
initfs distro.mk: functionalization 2011-11-03 20:39:00 +02:00
Makefile stage2: tunable squashfs compression 2012-04-09 22:03:29 +03:00
modules stage1/modules: added sdhci 2011-11-09 21:20:53 +02:00
README minor pkglist/docs tweaks 2011-11-13 00:37:45 +02:00

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Этот каталог содержит субпрофиль первой стадии загрузки;
здесь место syslinux (загрузчик) и propagator (ориентировка
на местности, вытягивание второй стадии с CD/FTP/...).

Скрипты запускаются извне формируемого образа (scripts.d/);
следует крайне бережно относиться к составу STAGE1_PACKAGES
и объёму этой стадии.

Обратите внимание: если не указать явно требуемый вариант
ядра посредством STAGE1_KFLAVOUR, будет взят последний
из перечисленных в KFLAVOURS; если не указать явно регэкс,
описывающий требуемые в инсталяторе модули, посредством
STAGE1_KMODULES_REGEXP -- будет подмножество модулей
из kernel-image (упаковываются в syslinux/alt0/full.cz).

Требуется для инсталяционных, live- и rescue-образов,
соответствующими фичами подключается автоматически
(в силу зависимости stage2 от stage1).

Результат -- каталог syslinux/ для копирования в образ.

TODO (3.2+): "The network drivers directory (drivers/net)
has been massively rearranged with most drivers moved into
media-specific or protocol-specific subdirectories."