[Buildroot] image size reduction

[Buildroot] image size reduction

[Ravi Chhabra]

Hi All,

I am trying to boot linux on quad core Aarch64 system with only 8MB on chip RAM which I plan to use for storage and loading the image.

I intend to shrink the size of image file by reducing all possible components and simplifying the build. I am using latest buildroot 14.11 release with ulibc option, no application and minimal busybox options which brought the root filesystem (unzipped cpio) size down to ~3MB which is still quite big.

I would be interested to reduce the size of kernel as well and further reduce the size of filesystem to reduce the size of image (axf file)

Kindly guide the right way to do that.

Thanks,
Ravi C

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[Buildroot] image size reduction

[Thomas Petazzoni]

Dear Ravi Chhabra,

On Tue, 13 Jan 2015 17:54:11 +0000, Ravi Chhabra wrote:

> I am trying to boot linux on quad core Aarch64 system with only 8MB
> on chip RAM which I plan to use for storage and loading the image.

Great to see people using Buildroot to bring up AArch64 systems!

> I intend to shrink the size of image file by reducing all possible
> components and simplifying the build. I am using latest buildroot
> 14.11 release with ulibc option, no application and minimal busybox
> options which brought the root filesystem (unzipped cpio) size down
> to ~3MB which is still quite big.

Well, 3 MB is generally considered quite small for a Linux root
filesystem. Here is what I could propose to further reduce the size:

 * Tune the Busybox configuration, to reduce the size of the Busybox
   binary. Run 'make busybox-menuconfig', and disable all applets you
   don't use.

 * Enable BR2_STATIC_LIBS=y (was named BR2_PREFER_STATIC_LIB=y). This
   way, Busybox will be linked statically, and you won't have any C
   library on your target.

However, I'm a bit surprised: how do you have uClibc support for
AArch64 ? Or are you building an ARMv7 root filesystem ?

> I would be interested to reduce the size of kernel as well and
> further reduce the size of filesystem to reduce the size of image
> (axf file)

Well, for the kernel, just adjust your kernel configuration and remove
stuff, I believe it's quite obvious.

Best regards,

Thomas Petazzoni
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com