I've tested this with the following setup:
- QEMU with its 'mips' target in little endian mode
- u-boot compiled for quemu-mips (little endian)
- ubldr compiled for mipsel
- a kernel quickly put together for the qemu-mips target that only supports basic UART (so we can see the bootlog).
Output of the whole thing booting can be seen below:
%%%> qemu-system-mipsel -M mips -bios u-boot.bin -nographic -net nic,macaddr=00:16:3e:00:00:01 -net tap -hda hda.img -cpu 24Kc
W: /etc/qemu-ifup: no bridge for guest interface found
Could not open option rom 'vgabios-cirrus.bin': No such file or directory
U-Boot 2016.03-rc1-dirty (Feb 04 2016 - 11:41:10 +0200)
Board: Qemu -M mips CPU: 24Kc proc_id=0x19300
DRAM: 128 MiB
Using default environment
In: serial
Out: serial
Err: serial
Net: NE2000
IDE: Bus 0: OK Bus 1: OK
Device 0: Model: QEMU HARDDISK Firm: 2.0.0 Ser#: QM00001
Type: Hard Disk
Capacity: 50.0 MB = 0.0 GB (102400 x 512)
Device 1: not available
Device 2: not available
Device 3: not available
Hit any key to stop autoboot: 0
qemu-mipsel # tftp; bootelf
Using NE2000 device
TFTP from server 192.168.78.1; our IP address is 192.168.78.10
Filename 'demo'.
Load address: 0x80500000
Loading: #################
5.6 MiB/s
done
Bytes transferred = 244995 (3bd03 hex)
## Starting application at 0x80800080 ...
Consoles: U-Boot console
Compatible U-Boot API signature found @87f6e0a8
FreeBSD/mipsel U-Boot loader, Revision 1.2
(root@stassi-bsd9, Wed Feb 3 17:44:10 EET 2016)
DRAM: 128MB
Number of U-Boot devices: 2
U-Boot env: loaderdev not set, will probe all devices.
Found U-Boot device: disk
Probing all disk devices...
Checking unit=0 slice=<auto> partition=<auto>... good.
Booting from disk0s1:
/
/boot/kernel/kernel data=0x3ebaa8+0x27ff8 syms=[0x4+0x43a90+0x4+0x5e7cf]
Hit [Enter] to boot immediately, or any other key for command prompt.
Booting [/boot/kernel/kernel]...
Kernel entry at 0x80100100...
Kernel args: (null)
U-Boot args (from -2141491201 args):
Environment:
???m??
disk0s1:
entry: mips_init()
Cache info:
picache_stride = 4096
picache_loopcount = 0
pdcache_stride = 1024
pdcache_loopcount = 2
cpu0: MIPS Technologies processor v0.147
MMU: Standard TLB, 16 entries (4K 16K 64K 256K 1M 16M 64M 256M pg sizes)
L1 i-cache: 2 ways of 64 sets, 16 bytes per line
L1 d-cache: 2 ways of 64 sets, 16 bytes per line
L2 cache: disabled
Config1=0x9e190c8e<WatchRegs,MIPS16,EJTAG>
Config2=0x80000000
Physical memory chunk(s):
0x514000 - 0x1ffffff, 28229632 bytes (6892 pages)
Maxmem is 0x2000000
KDB: debugger backends: ddb
KDB: current backend: ddb
Copyright (c) 1992-2016 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 11.0-CURRENT #0 733656d(local/sgalabov_mtk)-dirty: Wed Feb 3 19:56:05 EET 2016
root@stassi-bsd9:/usr/obj/mips.mipsel/src/sgalabov/sys/QEMU-MIPS mips
gcc version 4.2.1 20070831 patched [FreeBSD]
Preloaded elf kernel "kernel" at 0x8050dfe0.
real memory = 33554432 (32768K bytes)
Physical memory chunk(s):
0x005a8000 - 0x01f47fff, 26869760 bytes (6560 pages)
avail memory = 26456064 (25MB)
ULE: setup cpu 0
random: entropy device external interface
null: <full device, null device, zero device>
mem: <memory>
nfslock: pseudo-device
nexus0: <MIPS32 root nexus>
random: harvesting attach, 8 bytes (4 bits) from nexus0
clock0: <Generic MIPS32 ticker> on nexus0
Timecounter "MIPS32" frequency 50000000 Hz quality 800
Event timer "MIPS32" frequency 50000000 Hz quality 800
random: harvesting attach, 8 bytes (4 bits) from clock0
obio0 at mem 0x10000000-0x1fffffff on nexus0
uart0: <16550 or compatible> on obio0
uart0: console (-1,n,8,1)
uart0: fast interrupt
uart0: PPS capture mode 2 (DCD)
random: harvesting attach, 8 bytes (4 bits) from uart0
random: harvesting attach, 8 bytes (4 bits) from obio0
Device configuration finished.
Timecounters tick every 10.000 msec
tcp_init: net.inet.tcp.tcbhashsize auto tuned to 512
lo0: bpf attached
Trying to mount root from ufs:ada0 []...
mountroot: waiting for device ada0...
Mounting from ufs:ada0 failed with error 19.
Loader variables:
<snip>