All 2.6 linux kernels start the boot process by using initramfs. During the boot process a pivot root to a real root filesystem occurs, typically on a hard drive. Rob Landley first documented how one could create a root filesystem that resides solely in initramfs. Usually this method is deployed in embedded systems. In all versions of Tiny Core up to version 2.1, we booted a complete root filesystem from an initramfs.
Note that initramfs does not have a preset size. Therefore doing a 'df' command on the root filesystem would return 0. This caused problems with certain application installations, as part of their setup required a check to see if there was enough room to successfully complete the install.
It was requested in the forums to 'solve' this df return 0 issue.
To accomodate this request, I created a tmpfs filesystem of set size of 90% of free ram. Then I had to copy over all the files on the initramfs to the new tmpfs, and switch root to point to the new location of tmpfs. This is an overhead to perform such copy and effectively requires more initial ram as the copy takes place (2 set of files during copy). The end result effects the desired result, The 'df' command reports on free space available and now such applications successfuly install.
Some of the community where still not happy, as now we have higher ram requirement and slightly slower boot time, so for those who do not need free space reporting, can choose to use our original boot method of staying on the initramfs, i..e, embedded mode. Hence the 'embed' boot option.