[Buildroot] Need help with genimage

[Baruch Siach]

Hi Jörg,

On Sun, Jan 08, 2017 at 07:32:37PM +0100, Jörg Krause wrote:
> On Sun, 2017-01-08 at 19:45 +0200, Baruch Siach wrote:
> > On Sun, Jan 08, 2017 at 12:58:51PM +0100, Jörg Krause wrote:
> > > I am able to generate the sd card image and copy it to the sd card
> > > using Suses imagewriter. The board boots fine. However, the rootfs
> > > size
> > > is not 512MB as expected:
> > > 
> > > # df -hT
> > > Filesystem           Type            Size      Used Available Use%
> > > Mounted on
> > > /dev/root            ext4           38.7M     37.9M         0 100%
> > > /
> > > devtmpfs             devtmpfs      501.9M         0    501.9M   0%
> > > /dev
> > > tmpfs                tmpfs         502.4M         0    502.4M   0%
> > > /dev/shm
> > > tmpfs                tmpfs         502.4M      3.9M    498.4M   1%
> > > /tmp
> > > tmpfs                tmpfs         502.4M     24.0K    502.4M   0%
> > > /run
> > > 
> > > I am not able to create any file larger file on the filesystem nor
> > > start some programs.
> > > 
> > > What am I missing here? Can somebody enlighten me please :-)
> > 
> > Unless you set BR2_TARGET_ROOTFS_EXT2_BLOCKS and
> > BR2_TARGET_ROOTFS_EXT2_INODES 
> > you'll get a minimal ext2/3/4 filesystem with no free space.
> > Alternatively, 
> > you may run on target the resize2fs tool from the e2fsprogs package
> > on the 
> > root filesystem to expand the filesystem to the size of the
> > partition.
> 
> Which values should I use for blocks and inodes if I set the rootfs
> size to 512M in genimage.cfg? Any suggestions?

The Buildroot package/mke2img/mke2img script assumes a 1KB block size, so you 
need 512K blocks.

The number of inodes determines the number of file entries in the filesystem. 
A safe "inode ratio" default is one inode per 16384 bytes. That is the native 
e2fsprogs package mke2fs tool default, but YMMV.

baruch

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -