67 lines
2.4 KiB
Markdown
67 lines
2.4 KiB
Markdown
# The Abstract Machine (AM)
|
||
|
||
## How to build benchmark flash image
|
||
- clone `nexus-am` from github:
|
||
``` shell
|
||
git clone git@github.com:OpenXiangShan/nexus-am.git
|
||
```
|
||
- enter benchmark directory (using `apps/coremark` as an example):
|
||
```
|
||
cd /apps/coremark
|
||
make ARCH=riscv64-xs-flash
|
||
cd ./build
|
||
ls
|
||
```
|
||
- you will find a ".bin" file, this is a benchmark image in flash
|
||
|
||
## How to use the prepared flash image to do simulation
|
||
- assuming you have a `XiangShan` repo, the commit ID should be newer than 188f739de96af363761c0f2b80b95b70ad01e0fc
|
||
- make `emu` build
|
||
- use `-F` to load the image in flash:
|
||
```
|
||
./emu -F $AM_HOME//apps/coremark/build/coremark-riscv64-xs-flash.bin -i ../ready-to-run/coremark-2-iteration.bin 2>debug.log
|
||
```
|
||
> NOTE: use `-i` to specify the initial ram image, or a ramdom file if you do not care.
|
||
|
||
## Explanation of multi-processor bring-up drivers
|
||
|
||
The driver consists of the following functions (implemented in am/src/xs/isa/riscv/mpe.c) :
|
||
|
||
* `_mpe_init(void (*entry)())`: register an `entry` procedure that each processor will run into after initialization
|
||
|
||
* `_ncpu()`: return the total number of processors
|
||
|
||
* `_cpu()`: return the hartID of current processor (start from 0)
|
||
|
||
* `_atomic_xchg(intptr_t *addr, intptr_t newval)`: atomic exchange function，replace the value in *addr with newval and return the original value
|
||
|
||
* `_atomic_add(intptr_t *addr, intptr_t adder) `: atomic adding function，increment value in *addr with adder and return the original value
|
||
|
||
* `_barrier()`: barrier function，wait until all processors arrive here
|
||
|
||
(For more atomic operations, You can implement it yourself using a similar format as _atomic_add)
|
||
|
||
|
||
|
||
A simple demo is provided in tests/amtest/src/tests/mp.c Here is the instruction to build and run
|
||
|
||
```shell
|
||
cd nexus-am
|
||
make ARCH=riscv64-xs-dual mainargs='m2'
|
||
# Here m means multi-processor demo, 2 means dual core
|
||
$(PATH_OF_DUALCORE_XS)/build/emu -i build/amtest-riscv64-xs-dual.bin --diff=$(PATH_OF_DUALCORE_XS)/ready-to-run/riscv64-nemu-interpreter-dual-so
|
||
```
|
||
|
||
The output should be like this:
|
||
|
||
```shell
|
||
My CPU ID is 0, nrCPU is 2
|
||
My CPU ID is 1, nrCPU is 2
|
||
sum = 193 atomic_sum = 200
|
||
Finalize CPU ID: 1
|
||
sum = 193 atomic_sum = 200
|
||
Finalize CPU ID: 0
|
||
```
|
||
|
||
Note that both `sum` and `atomic_sum` are incremented 100 times per CPU parallelly. However, `atomic_sum` utilizes atomic primitive. Thus, we have `sum` <= 200 && `atomic_sum` == 200.
|