After quite some time I finally update my blog ;). A lot has happened in the last few weeks... The Haiku loader that gets loaded by u-boot finally is able to load the kernel and start it and we even have minimal framebuffer support running.
haiku_loader
In the previous posts I said that we would use the U-Boot API to write the loader, the problem with that is, that the API is not accessible on most U-Boots so we could not use it on early boot and had to write our own functions for serial output etc. Because of that the kernel is now loaded from a ramdisk instead of directly loading it from the sd-card as planned (but that might change later...). It also has the disadvantage, that the loader code is not completely platform independent anymore so we would have to rewrite it to be used on a PPC board with U-Boot for example.
Since we still need to know where to find the ramdisk for example (unless we hardcode it..) we decided to use the U-Boot image format that allows packing the loader and the ramdisk in one image and tell the loader where everything is and what parameters to pass to the kernel etc.. For this task U-Boot has OS-specific code since there is no standardized way of doing this. Since there was no Haiku specific code we would either have to convince the U-Boot developers to add Haiku support or simply masquerade as an other operating system. We choose the second option and François Revol added support for the netbsd way of booting so that we get the position of the ramdisk and the kernel parameters and some other info that is not yet used. He also created an jamtarget to allow to build an image directly.
