[Samsung Galaxy Star] Doc_cheilvenerdi.org:
Wait a minute! I'm not writing about Overclock, I simply compiled "Galaxy Star Kernel" from Source...

...for fun...

...with CPU frequency scaling...

Prerequisites:

a 64bit Linux Machine with a working build environment

a local copy of a Jellybean arm cross toolchain

tools to unpack and repack a boot image from a Stock firmware

Kernel source downloaded from Samsung Open Source Release Center

How I did it:

First of all I unzip the kernel source into a linux folder and modify one line from

CROSS_COMPILE ?= /opt/toolchains/arm-eabi-4.4.3/bin/arm-eabi-

to

CROSS_COMPILE ?= /home/doc/builds/CYANOGENMOD_10.0__4.1.2_JELLYBEAN/prebuilt/linux-x86/toolchain/arm-eabi-4.4.3/bin/arm-eabi-

which is the full local path to my cross prebuilt toolchain previously downloaded from Cyanogenmod repositories...

Then I follow the kernel readme to prepare it for my Galaxy Star:

doc@saucy:~/tmp/kernel-gt5280$ [b]make mint-vlx-rev03_defconfig[/b]
...
doc@saucy:~/tmp/kernel-gt5280$

And finally I simply issue the master command:

doc@saucy:~/tmp/kernel-gt5280$ [b]make zImage[/b]
...

...

...
LD vmlinux
SYSMAP System.map
SYSMAP .tmp_System.map
OBJCOPY arch/arm/boot/Image
Kernel: arch/arm/boot/Image is ready
AS arch/arm/boot/compressed/head.o
GZIP arch/arm/boot/compressed/piggy.gzip
AS arch/arm/boot/compressed/piggy.gzip.o
CC arch/arm/boot/compressed/misc.o
CC arch/arm/boot/compressed/decompress.o
SHIPPED arch/arm/boot/compressed/lib1funcs.S
AS arch/arm/boot/compressed/lib1funcs.o
LD arch/arm/boot/compressed/vmlinux
OBJCOPY arch/arm/boot/zImage
Kernel: arch/arm/boot/zImage is ready
doc@saucy:~/tmp/kernel-gt5280$

Unfortunately, repacking the Compressed Kernel (zImage 3,5Mb) with the ramdisk into an Odin boot.img leads to a "not booting" system stuck at samsung logo...

Repacking instead the Uncompressed Kernel (Image 7,1 Mb) leads to normal boot with the system up and running (victory :)):

Now looking for frequency scaling:

...searching inside Kernel configuration with the command

doc@saucy:~/tmp/kernel-gt5280$ [b]make menuconfig[/b]

I find this menu:

.config - Linux/arm 3.0.8 Kernel Configuration
──────────────────────────────────────────────────────────────────────────────
┌───────────────────────── CPU Power Management ──────────────────────────┐
│ Arrow keys navigate the menu. <Enter> selects submenus --->. │
│ Highlighted letters are hotkeys. Pressing <Y> includes, <N> excludes, │
│ <M> modularizes features. Press <Esc><Esc> to exit, <?> for Help, </> │
│ for Search. Legend: [*] built-in [ ] excluded <M> module < > │
│ ┌─────────────────────────────────────────────────────────────────────┐ │
│ │ CPU Frequency scaling ---> │ │
│ │ [color=red][ ] CPUfreq support for Spreadtrum SC8810 CPUs[/color] │ │
│ │ [ ] CPU idle PM support │ │
│ │ │ │
│ └─────────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────────┤
│ <Select> < Exit > < Help > │
└─────────────────────────────────────────────────────────────────────────┘

where I simply switch on the frequency scaling for the Galaxy CPU:

.config - Linux/arm 3.0.8 Kernel Configuration
──────────────────────────────────────────────────────────────────────────────
┌───────────────────────── CPU Power Management ──────────────────────────┐
│ Arrow keys navigate the menu. <Enter> selects submenus --->. │
│ Highlighted letters are hotkeys. Pressing <Y> includes, <N> excludes, │
│ <M> modularizes features. Press <Esc><Esc> to exit, <?> for Help, </> │
│ for Search. Legend: [*] built-in [ ] excluded <M> module < > │
│ ┌─────────────────────────────────────────────────────────────────────┐ │
│ │ CPU Frequency scaling ---> │ │
│ │ [color=green][[b]*[/b]] CPUfreq support for Spreadtrum SC8810 CPUs[/color] │ │
│ │ [ ] CPU idle PM support │ │
│ │ │ │
│ └─────────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────────┤
│ <Select> < Exit > < Help > │
└─────────────────────────────────────────────────────────────────────────┘

After another Odin boot.img...

here we are:

Easy Play :cool:

Everything shared starting from here: My Google Drive

WARNING: I started from a GT-S5280XXAMF1 Stock Firmware, knowing exactly wat I was doing...

Beware, use my work as you wish but "

at your own risk

"!

And now what's Next?

...who knows...

...surely I'm not skilled enough to overclock this Kernel source or add governors...

I just made a "one shot compilation" and I was lucky :)!