diff --git a/docs/en/guide/extension-notes.md b/docs/en/guide/extension-notes.md
index 914281f2..1d9209c9 100644
--- a/docs/en/guide/extension-notes.md
+++ b/docs/en/guide/extension-notes.md
@@ -76,8 +76,7 @@ and this extension cannot be compiled into php by static linking, so it cannot b
 
 ## xdebug
 
-1. Xdebug is a Zend extension. The functions of Xdebug depend on PHP's Zend engine and underlying code. 
-If you want to statically compile it into PHP, you may need a huge amount of patch code, which is not feasible.
+1. Xdebug is only buildable as a shared extension. On Linux, you need to use static-php-cli with SPC_LIBC=glibc and then compile php-xdebug from source with the option `--with-php-config=/path/to/buildroot/bin/php-config`.
 2. The macOS platform can compile an xdebug extension under PHP compiled on the same platform, 
 extract the `xdebug.so` file, and then use the `--no-strip` parameter in static-php-cli to retain the debug symbol table and add the `ffi` extension. 
 The compiled `./php` binary can be configured and run by specifying the INI, eg `./php -d 'zend_extension=/path/to/xdebug.so' your-code.php`.
@@ -149,3 +148,9 @@ Parallel is only supported on PHP 8.0 ZTS and above.
 
 1. The [SPX extension](https://github.com/NoiseByNorthwest/php-spx) only supports NTS mode.
 2. SPX does not support Windows, and the official repository does not support static compilation. static-php-cli uses a [modified version](https://github.com/static-php/php-spx).
+
+## mimalloc
+
+1. This is not technically an extension, but a library.
+2. Building with `--with-libs="mimalloc"` on Linux or macOS will override the default allocator.
+3. This is experimental for now, but is recommended in threaded environments.
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