Michael Walle | 4566434 | 2011-02-17 23:45:15 +0100 | [diff] [blame] | 1 | LatticeMico32 target |
| 2 | -------------------- |
| 3 | |
| 4 | General |
| 5 | ------- |
| 6 | All opcodes including the JUART CSRs are supported. |
| 7 | |
| 8 | |
| 9 | JTAG UART |
| 10 | --------- |
| 11 | JTAG UART is routed to a serial console device. For the current boards it |
| 12 | is the second one. Ie to enable it in the qemu virtual console window use |
| 13 | the following command line parameters: |
| 14 | -serial vc -serial vc |
| 15 | This will make serial0 (the lm32_uart) and serial1 (the JTAG UART) |
| 16 | available as virtual consoles. |
| 17 | |
| 18 | |
| 19 | Programmatically terminate the emulator |
| 20 | ---------------------------------------- |
| 21 | Originally neither the LatticeMico32 nor its peripherals support a |
| 22 | mechanism to shut down the machine. Emulation aware programs can write to a |
| 23 | to a special register within the system control block to shut down the |
| 24 | virtual machine. For more details see hw/lm32_sys.c. The lm32-evr is the |
| 25 | first BSP which instantiate this model. A (32 bit) write to 0xfff0000 |
| 26 | causes a vm shutdown. |
| 27 | |
| 28 | |
| 29 | Special instructions |
| 30 | -------------------- |
| 31 | The translation recognizes one special instruction to halt the cpu: |
| 32 | and r0, r0, r0 |
| 33 | On real hardware this instruction is a nop. It is not used by GCC and |
| 34 | should (hopefully) not be used within hand-crafted assembly. |
| 35 | Insert this instruction in your idle loop to reduce the cpu load on the |
| 36 | host. |
| 37 | |
| 38 | |
| 39 | Ignoring the MSB of the address bus |
| 40 | ----------------------------------- |
| 41 | Some SoC ignores the MSB on the address bus. Thus creating a shadow memory |
| 42 | area. As a general rule, 0x00000000-0x7fffffff is cached, whereas |
| 43 | 0x80000000-0xffffffff is not cached and used to access IO devices. This |
| 44 | behaviour can be enabled with: |
| 45 | cpu_lm32_set_phys_msb_ignore(env, 1); |
| 46 | |