website: Improve instructions for linking against m5ops
The existing instructions for linking C/C++ code against m5ops are
quite complicated and involve building parts of m5ops into your
program. This change updates the instructions to describe linking
against the libm5.a static library that is generated alongside the m5
tool.
Change-Id: I38d728eeecb21895424c954fcf03fcbbd9238dc1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/40116
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
diff --git a/_pages/documentation/general_docs/m5ops.md b/_pages/documentation/general_docs/m5ops.md
index ff01bad..d5a6eaf 100644
--- a/_pages/documentation/general_docs/m5ops.md
+++ b/_pages/documentation/general_docs/m5ops.md
@@ -8,11 +8,11 @@
# M5ops
-This page explains the special opcodes that can be used in M5 to do checkpoints etc. The m5 utility program (on our disk image and in util/m5/*) provides some of this functionality on the command line. In many cases it is best to insert the operation directly in the source code of your application of interest. You should be able to link with the appropriate m5op_ARCH.o file and the m5ops.h header file has prototypes for all the functions.
+This page explains the special opcodes that can be used in M5 to do checkpoints etc. The m5 utility program (on our disk image and in util/m5/*) provides some of this functionality on the command line. In many cases it is best to insert the operation directly in the source code of your application of interest. You should be able to link with the appropriate libm5.a file and the m5ops.h header file has prototypes for all the functions.
-## Building M5
+## Building M5 and libm5
-In order to build m5 for your target ISA, run the following command in the util/m5/ directory.
+In order to build m5 and libm5.a for your target ISA, run the following command in the util/m5/ directory.
```bash
scons build/{TARGET_ISA}/out/m5
@@ -91,6 +91,20 @@
gem5's special opcodes (psuedo instructions) can be used with Fortran programs. In the Fortran code, one can add calls to C functions that invoke the special opcode. While creating the final binary, compile the object files for the Fortran program and the C program (for opcodes) together. I found the documentation provided [here](https://gcc.gnu.org/wiki/GFortranGettingStarted) useful. Read the section **-****- Compiling a mixed C-Fortran program**.
-## Linking M5 to your code
+## Linking M5 to your C/C++ code
-In order to link m5 to your code you have to add ```gem5/include/gem5/asm/generic/m5ops.h``` and ```gem5/util/m5/src/m5_mmap.h``` to your include path and add ```gem5/util/m5/src/m5_mmap.c``` and ```gem5/util/m5/src/{TARGET_ISA}/m5op.S``` to your source path and add m5op_{TARGET_ISA} and m5_mmap as objects to your object list. For an example on how to do this with PARSEC benchmark look [here](https://github.com/darchr/parsec-benchmark/blob/gem5-20-annotations/pkgs/libs/hooks/src/Makefile.shared)
+In order to link m5 to your code, first build `libm5.a` as described in the section above.
+
+Then
+
+* Include `gem5/m5ops.h` in your source file(s)
+* Add `gem5/include` to your compiler's include search path
+* Add `gem5/util/m5/build/{TARGET_ISA}/out` to the linker search path
+* Link against `libm5.a`
+
+For example, this could be achieved by adding the following to your Makefile:
+
+```
+CFLAGS += -I$(GEM5_PATH)/include
+LDFLAGS += -L$(GEM5_PATH)/util/m5/build/$(TARGET_ISA)/out -lm5
+```
