ea1abz%gmail.com@localhost (Ramiro Aceves) writes:
In my armv6 RaspberrypiZeroW, there is no /netbsd kernel file and
/boot/kernel.img seems to be the loaded kernel.
netbsd-raspaZeroW$ file kernel.img
lhs/off overflow 2148331788 0
kernel.img: data
/boot/kernel.img is what the RPI firmware regularly loads. You still
need (a similar) /netbsd for some NetBSD tools.
The firmware is actually a bit smarter. Depending on the RPI model
it looks for 64bit and 32bit kernels and searches for kernel8.img
or kernel7.img respectively and uses kernel.img as fallback. You
can also specify which kernel to boot and make that depend on
a GPIO signal (e.g. connect a switch).
On the other side, in my UEFI firmwared Raspberrypi4, netbsd.img is not
used (I believe it is only used when no UEFI fw is installed). There is
a /netbsd kernel in the usual standard place:
The process is controlled by entries in config.txt.
In this case the firmware loads UEFI, UEFI loads bootaa64.efi
and bootaa64.efi loads /netbsd.
The RPI documentation gives lots of details:
https://www.raspberrypi.com/documentation/computers/config_txt.html
E.g.:
# start in 64bit mode (default is 32bit for RPI0-3 compatibility)
arm_64bit=1
# configure GPIO 14+15 as UART TX+RX lines
enable_uart=1
# RPI4 specific. The chip has several interrupt controllers, this
# configures it to use the (arm standard) GIC-400 controller.
enable_gic=1
# load the "armstub" code from file, the default is to use code
# embedded in start4.elf. The embedded code sets up low-level
# hardware like the interrupt controller. The UEFI code
# needs to do that by itself.
armstub=RPI_EFI.fd
# Don't prepare legacy boot options in memory
# However, the value 2 is not documented.
disable_commandline_tags=2
# move the DTB into this memory area for UEFI to find it
device_tree_address=0x3e0000
device_tree_end=0x400000
netbsd-raspa4$ file netbsd.img
netbsd.img: Linux kernel ARM64 boot executable Image, little-endian, 4K
pages
note "Linux" there....
The firmware loads a Linux kernel image and NetBSD hides as that. The file
command just reports the fact.