Clarify LD_PRELOAD on dynamically-linked ELF
LD_PRELOAD is an environment variable that can be set to load ELF
shared objects before all others. Linux and BSD are known to fit.
This change also unifies the use of command line, ensuring the prefix
"> " prompt.
@@ -13,7 +13,7 @@ Initially developed by Daan Leijen for the run-time systems of the
[Koka](https://github.com/koka-lang/koka) and [Lean](https://github.com/leanprover/lean) languages.
It is a drop-in replacement for `malloc` and can be used in other programs
-without code changes, for example, on Unix you can use it as:
+without code changes, for example, on dynamically linked ELF-based systems (Linux, BSD, etc.) you can use it as:
```
> LD_PRELOAD=/usr/bin/libmimalloc.so myprogram
```
@@ -117,7 +117,7 @@ Notes:
The preferred usage is including `<mimalloc.h>`, linking with
the shared- or static library, and using the `mi_malloc` API exclusively for allocation. For example,
```
-gcc -o myprogram -lmimalloc myfile.c
+> gcc -o myprogram -lmimalloc myfile.c
```
mimalloc uses only safe OS calls (`mmap` and `VirtualAlloc`) and can co-exist
@@ -207,20 +207,21 @@ This is the recommended way to override the standard malloc interface.
### Linux, BSD
-On these systems we preload the mimalloc shared
+On these ELF-based systems we preload the mimalloc shared
library so all calls to the standard `malloc` interface are
resolved to the _mimalloc_ library.
-
-- `env LD_PRELOAD=/usr/lib/libmimalloc.so myprogram`
+```
+> env LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
+```
You can set extra environment variables to check that mimalloc is running,
like:
```
-env MIMALLOC_VERBOSE=1 LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
+> env MIMALLOC_VERBOSE=1 LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
```
or run with the debug version to get detailed statistics:
```
-env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
+> env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
```
### MacOS
@@ -228,8 +229,9 @@ env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
On macOS we can also preload the mimalloc shared
library so all calls to the standard `malloc` interface are
resolved to the _mimalloc_ library.
-
-- `env DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/lib/libmimalloc.dylib myprogram`
+```
+> env DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/lib/libmimalloc.dylib myprogram
+```
Note that certain security restrictions may apply when doing this from
the [shell](https://stackoverflow.com/questions/43941322/dyld-insert-libraries-ignored-when-calling-application-through-bash).
@@ -257,16 +259,15 @@ robust; try this out if you experience troubles.
## Static override
-On Unix systems, you can also statically link with _mimalloc_ to override the standard
+On Unix-like systems, you can also statically link with _mimalloc_ to override the standard
malloc interface. The recommended way is to link the final program with the
_mimalloc_ single object file (`mimalloc-override.o`). We use
an object file instead of a library file as linkers give preference to
that over archives to resolve symbols. To ensure that the standard
malloc interface resolves to the _mimalloc_ library, link it as the first
object file. For example:
-
```
-gcc -o myprogram mimalloc-override.o myfile1.c ...
+> gcc -o myprogram mimalloc-override.o myfile1.c ...
```
