feat: update 'callPackage'

docs/nixpkgs/callpackage.md

@@ -13,5 +13,58 @@ When the `xxx.nix` used in `pkgs.callPackge xxx.nix {...}` is a function (most N
 3. Then `pkgs.callPackge` will merge its second parameter `{...}` with the attribute set obtained in the previous step, and then pass it to the function imported from `xxx.nix` and execute it.
 4. Finally we get a Derivation as the result of the function execution.
 
-So the common usage of `pkgs.callPackage` is to import customized Nix packages and used them in Nix Module.
-For example, we wrote a `hello.nix` ourselves, and then we can use `pkgs.callPackage ./hello.nix {}` in any Nix Module to import and use it.
+The common usage of `pkgs.callPackage` is to import customized Nix packages and used them in Nix Module.
+
+
+For example, we have customized a NixOS kernel configuration `kernel.nix`, and used the SBC's name and kernel source as its variable parameters:
+
+```nix
+{
+  lib,
+  stdenv,
+  linuxManualConfig,
+
+  src,
+  boardName,
+  ...
+}:
+(linuxManualConfig {
+  version = "5.10.113-thead-1520";
+  modDirVersion = "5.10.113";
+
+  inherit src lib stdenv;
+  
+  # file path to the generated kernel config file(the `.config` generated by make menuconfig)
+  #
+  # here is a special usage to generate a file path from a string
+  configfile = ./. + "${boardName}_config";
+
+  allowImportFromDerivation = true;
+})
+```
+
+Then we can use `pkgs.callPackage ./kernel.nix {}` in any Nix Module to import and use it, and replace any of its parameters:
+
+```nix
+{ lib, pkgs, pkgsKernel, kernel-src, ... }: 
+
+{
+  # ......
+
+  boot = {
+    # ......
+    kernelPackages = pkgs.linuxPackagesFor (pkgs.callPackage ./pkgs/kernel {
+        src = kernel-src;  # kernel source is passed as a `specialArgs` and injected into this module.
+        boardName = "licheepi4a";  # the board name, used to generate the kernel config file path.
+    });
+
+  # ......
+}
+```
+
+Just like the example above, we can use `pkgs.callPackage` to pass different `src` and `boardName` to the function defined in `kernel.nix` through `pkgs.callPackage`, so that different kernel packages can be generated. 
+The `kernel.nix` can be used to adapt to different kernel sources and different development boards by changing the parameters passed to it.
+
+## References
+
+- [Chapter 13. Callpackage Design Pattern - Nix Pills](https://nixos.org/guides/nix-pills/callpackage-design-pattern.html)

docs/zh/nixpkgs/callpackage.md

@@ -15,7 +15,55 @@
 3. 接着 `pkgs.callPackge` 会将其第二个参数 `{...}` 与前一步得到的参数集（attribute set）进行合并，得到一个新的参数列表，然后将其传递给该函数并执行。
 4. 函数执行结果是一个 Derivation，也就是一个软件包。
 
-这个函数比较常见的用途是用来导入一些自定义的 Nix 包，比如说我们自己写了一个 `hello.nix`，然后就可以在任意 Nix Module 中使用 `pkgs.callPackage ./hello.nix {}` 来导入并使用它。
+这个函数比较常见的用途是用来导入一些自定义的 Nix 包。
+
+比如说我们自定义了一个 NixOS 内核配置 `kernel.nix`，并且将开发版名称与内核源码作为了可变更参数：
+
+```nix
+{
+  lib,
+  stdenv,
+  linuxManualConfig,
+
+  src,
+  boardName,
+  ...
+}:
+(linuxManualConfig {
+  version = "5.10.113-thead-1520";
+  modDirVersion = "5.10.113";
+
+  inherit src lib stdenv;
+  
+  # file path to the generated kernel config file(the `.config` generated by make menuconfig)
+  #
+  # here is a special usage to generate a file path from a string
+  configfile = ./. + "${boardName}_config";
+
+  allowImportFromDerivation = true;
+})
+```
+
+那么就可以在任意 Nix Module 中使用 `pkgs.callPackage ./hello.nix {}` 来导入并使用它，并且替换它的任意参数。
+
+```nix
+{ lib, pkgs, pkgsKernel, kernel-src, ... }: 
+
+{
+  # ......
+
+  boot = {
+    # ......
+    kernelPackages = pkgs.linuxPackagesFor (pkgs.callPackage ./pkgs/kernel {
+        src = kernel-src;  # kernel source is passed as a `specialArgs` and injected into this module.
+        boardName = "licheepi4a";  # the board name, used to generate the kernel config file path.
+    });
+
+  # ......
+}
+```
+
+就如上面所展示的，通过 `pkgs.callPackage` 我们可以给 `kernel.nix` 定义的函数传入不同的 `src` 与 `boardName`，来生成不同的内核包，这样就可以使用同一份 `kernel.nix` 来适配不同的内核源码与不同的开发板了。
 
 
 ## 参考