qemu/lm32 at c26a5ab71338a53340257233bd172bbe22c06b16 - qemu

History

Alex Bennée 1f5c00cfdb qom/cpu: move tlb_flush to cpu_common_reset It is a common thing amongst the various cpu reset functions want to flush the SoftMMU's TLB entries. This is done either by calling tlb_flush directly or by way of a general memset of the CPU structure (sometimes both). This moves the tlb_flush call to the common reset function and additionally ensures it is only done for the CONFIG_SOFTMMU case and when tcg is enabled. In some target cases we add an empty end_of_reset_fields structure to the target vCPU structure so have a clear end point for any memset which is resetting value in the structure before CPU_COMMON (where the TLB structures are). While this is a nice clean-up in general it is also a precursor for changes coming to cputlb for MTTCG where the clearing of entries can't be done arbitrarily across vCPUs. Currently the cpu_reset function is usually called from the context of another vCPU as the architectural power up sequence is run. By using the cputlb API functions we can ensure the right behaviour in the future. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>		2017-01-13 14:24:31 +00:00
..
cpu-qom.h
cpu.c
cpu.h
gdbstub.c
helper.c
helper.h
lm32-semi.c
machine.c
Makefile.objs
op_helper.c
README
TODO
translate.c

README

LatticeMico32 target
--------------------

General
-------
All opcodes including the JUART CSRs are supported.


JTAG UART
---------
JTAG UART is routed to a serial console device. For the current boards it
is the second one. Ie to enable it in the qemu virtual console window use
the following command line parameters:
  -serial vc -serial vc
This will make serial0 (the lm32_uart) and serial1 (the JTAG UART)
available as virtual consoles.


Semihosting
-----------
Semihosting on this target is supported. Some system calls like read, write
and exit are executed on the host if semihosting is enabled. See
target/lm32-semi.c for all supported system calls. Emulation aware programs
can use this mechanism to shut down the virtual machine and print to the
host console. See the tcg tests for an example.


Special instructions
--------------------
The translation recognizes one special instruction to halt the cpu:
  and r0, r0, r0
On real hardware this instruction is a nop. It is not used by GCC and
should (hopefully) not be used within hand-crafted assembly.
Insert this instruction in your idle loop to reduce the cpu load on the
host.


Ignoring the MSB of the address bus
-----------------------------------
Some SoC ignores the MSB on the address bus. Thus creating a shadow memory
area. As a general rule, 0x00000000-0x7fffffff is cached, whereas
0x80000000-0xffffffff is not cached and used to access IO devices. This
behaviour can be enabled with:
  cpu_lm32_set_phys_msb_ignore(env, 1);