Hello,
The goal of these changes is to refresh the QEMU ref405ep machine and
enable boot from a Linux kernel without relying on a U-Boot firmware.
The reason for doing so is that we are unable to find a "ppc405_rom.bin"
firmware image or a flash image for the 405EP machines.
Thomas fought is way through on a v2015.10 U-Boot and taihu defconfig
and provided a compatible image available here :
https://gitlab.com/huth/u-boot/-/tree/taihu/
With this image, QEMU reaches the U-Boot prompt (with a simple
workaround in the SDRAM).
On the Linux side, the only available 405EP CPU board is the one for
the ESTeem 195E (PPC405EP) SBC (hotfoot). It was added in 2009. The
board information structure in Linux, in U-Boot and in QEMU are not in
sync and the hotfoot board also adds its own flavor because the FW was
an ancient U-Boot without dual ethernet support [1].
For this kernel to be loaded by the U-Boot image provided by Thomas,
we either need to modify U-Boot or Linux. The same question arise for
QEMU, see the last patch of this series which is controversial. Please
advise !