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The 'qemuprep'/'qemuprep-altivec' BSPs are variants of
'motorola_powerpc' that can run under QEMU. They are *not*
binary compatible with other variants of 'motorola_powerpc'
(nor with each other).
Most significant differences to real hardware:
- no OpenPIC, just a 8259 PIC (even though qemu implements an openpic
at least to some extent it is not configured into the prep platform
as of qemu-0.14.1).
- no VME (absense of the VME controller is detected by the BSP)
- the only network chip supported by both, qemu and vanilla RTEMS
is the ISA NE2000 controller. Note that the default interrupt line
settings used by RTEMS and QEMU differ: RTEMS uses 5 and QEMU 9.
This can be addressed by passing a RTEMS commandline option
--ne2k-irq=9.
Other controllers (i8559, e1000, pcnet) implemented by qemu can
also be used but require unbundled RTEMS drivers (libbsdport).
Note that the bundled 'if_fxp' has not been ported to PPC and works
on x86 only.
- unlike a real motorola board you can run qemu emulating a 7400 CPU
which features altivec. I.e., you can use this BSP (altivec-enabled
variant) to test altivec-enabled code.
Compatibility: qemu had quite a few bugs related to the PREP platform.
Version 0.12.4, for example, required patches. 0.14.1 seems to have
fixed the show-stoppers. Hence, you *need* at least qemu-0.14.1 for
this BSP; it should work without the need for patching QEMU.
BIOS: qemu requires you to use a BIOS. The one that came with qemu
0.12.4 didn't work for me so I created a minimal dummy that provides
enough functionality for the RTEMS bootloader to work.
BSP Variants:
You can compile the BSP for either a 604 CPU or a 7400 (altivec-enabled).
Note that you cannot run the altivec-enabled BSP variant on a CPU w/o
altivec/SIMD hardware. The non-altivec variant is called 'qemuprep'
and the altivec-enabled one 'qemuprep-altivec'. Hence, you can
configure RTEMS:
604/non-altivec variant only:
configure --target=powerpc-rtems --enable-rtemsbsp=qemuprep
7400/altivec variant only:
configure --target=powerpc-rtems --enable-rtemsbsp=qemuprep-altivec
both variants:
configure --target=powerpc-rtems --enable-rtemsbsp='qemuprep qemuprep-altivec'
Building QEMU:
In case you have no pre-built qemu-0.14.1 you can
compile it yourself:
cd qemu-0.14.1
configure --target-list=ppc-softmmu
make
Running QEMU:
A number of command-line options are important (BTW: make sure
you run the PPC/PREP emulator and not a natively installed i386/PC
emulating 'qemu')
-M prep --- select machine type: prep
-cpu 604 --- select 604 CPU for non-altivec variant
-cpu 7400 --- select 7400 CPU for altivec variant
NOTE: the 7455 and 7457 emulations are buggy as of
qemu-0.14.1 and they won't work.
-bios <rtems-install-prefix>/powerpc-rtems/qemuprep/qemu_fakerom.bin
-bios <rtems-install-prefix>/powerpc-rtems/qemuprep-altivec/qemu_fakerom.bin
--- select proprietary dummy 'BIOS'
-nographic --- redirect serial/IO to console where qemu is run
-kernel <path> --- path to your RTEMS executable (.ralf file, e.g., 'hello.ralf')
-no-reboot --- terminate after one run
-append <arg> --- RTEMS kernel comand line (use e.g., to modify
ne2000 driver interrupt line)
Networking:
(We assume your RTEMS application is correctly configured and
built for networking using the ne2k adapter [other adapters
can be used with unbundled/libbsdport drivers])
I use networking with a 'tap' interface on the host machine
and can then communicate with the emulated target in any
desired way.
On (linux) host:
# create a 'permanent' tap device that can be used by myself
# (as non-root user).
sudo tunctl -u `id -u`
# configure tap0 interface
sudo ifconfig tap0 10.1.1.1 netmask 255.255.255.0 up
# provide a suitable dhcpd config file (for the emulated
# platform to boot: IP address etc.
#
# execute dhcp on host
sudo dhcpd -d tap0
Start emulated prep platform:
ppc-softmmu/qemu-system-ppc \
-M prep \
-cpu 7400 \
-bios <rtems-prefix>/powerpc-rtems/qemuprep-altivec/lib/qemu_fakerom.bin \
-kernel <my_path>/my_app.ralf \
-append --ne2k-irq=9 \
-nographic \
-no-reboot \
-net nic,model=ne2k_isa \
-net tap,vlan=0,ifname=tap0,script=no,downscript=no
Again: if you use the non-altivec BSP variant, use -cpu 604
and if you use the altivec-enabled variant then you MUST use
-cpu 7400.
Have fun.
Till Straumann, 2011/07/18
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