Sharp SL-5500 File Manager Guide Instrukcja Użytkownika Pobierz pdf (Strona 21)

CHAPTER 4. LIVERAM DISKS 4.5. KEXECBOOTS

Zauruses with default bootloader and MTD partitioning have only

1.2 Mb

of free space in

NAND to hold kernel. Modern kernels are too big to ﬁt into that constraints without signiﬁcal

loss in features (even with separate modules),

Some devices (such as Zauruses) have no possibility to boot from other media (SD/MMC/CF)

with default bootloader.

Angstr

om was based on top of OE (OpenEmbedded), OpenZaurus and OpenSimpad. Zaurus’ OS

was the most supported platform, at that times. To address these problems, Thomas Kunze wrote

ﬁrst versions of kexecboot.

4.5.4 Way of Work

When kexecboot’s kernel is loaded, it runs kexecboot binary as init process. This process does the

following things (for the current development version, i.e. 0.6):

1. scan all known partitons on devices (from /proc/partitions),

check that the partition’s ﬁlesystem is known (according to

fstype.c

from

klibc

and

/proc/filesystems),

3. mount that partition and check for /boot/boot.cfg there:

(a)

boot.cfg

is found, then parse it and do some additional things (load custom icon for

example);

(b) if boot.cfg is not found, then check for default kernels (/boot/zImage, /zImage),

4. check for zImage, the replacement Linux kernel (compressed),

5. create and show GUI with collected partitions,

6. wait for selection and then kexec selected kernel.

Kexecboot binary can be started as non-init process too, so you can run it in your own image at any

time too.

Latest kexecboot release was 0.5. The development version is 0.6.

4.5.5 Consequences

As the kexecboot kernel embeds a very limited initramfs, it contains just a couple of static binaries

(kexec and kexecboot). Kexec is the tool (see kexec-tools), kexecboot is the “init,” a custom-purposed

binary launching kexec with appropriate args. The name “kexecboot” was given by the author of

the project.

So, if you want to create a standard “liveramdisk” image, just enable kexec during the conﬁg of

the kernel and deploy kexec-tools in your image.

4.5.6 Screenshots

Here are pictures (taken from [2]) of a v0.4 kexecboot.

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 47 48

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