### Author:  [@simpleboy0](https://discourse.nixos.org/u/simpleboy0)
#### Post date: [November 22, 2023, 9:26am UTC](https://discourse.nixos.org/t/build-uimage-instead-of-zimage/35855/1 "2023-11-22T09:26:45Z")
Hello,
Anyone knows how to build `uImage` instead of `zImage` here?
I don’t know how can I use this option:
>
Here’s the sample of my module:
```auto
let
# dont use overlays for the qemu, it causes a lot of wasted time on recompiles
x86pkgs = import pkgs.path { system = "x86_64-linux"; };
build = config.system.build;
# armv7l cross-compile and boot fixes
customKernel = pkgs.linux.override {
extraConfig = ''
OVERLAY_FS y
'';
};
customKernelPackages = pkgs.linuxPackagesFor customKernel;
in {
boot.kernelPackages = customKernelPackages;
nixpkgs.system = "armv7l-linux";
system.build.zynq_image = let
cmdline = "root=/dev/mmcblk0 console=ttyPS0,115200n8 systemConfig=${builtins.unsafeDiscardStringContext build.toplevel}";
qemuScript = ''
#!/bin/bash -v
export PATH=${x86pkgs.qemu}/bin:$PATH
set -x
base=$(dirname $0)
mkdir ./tmp/
cp $base/root.squashfs ./tmp/
chmod +w ./tmp/root.squashfs
truncate -s 64M ./tmp/root.squashfs
qemu-system-arm \
-M xilinx-zynq-a9 \
-serial /dev/null \
-serial stdio \
-display none \
-dtb $base/zynq-zc706.dtb \
-kernel $base/zImage \
-initrd $base/initrd \
-drive file=./tmp/root.squashfs,if=sd,format=raw \
-append "${cmdline}"
'';
in pkgs.runCommand "zynq_image" {
inherit qemuScript;
passAsFile = ["qemuScript"];
preferLocalBuild = true;
} ''
mkdir $out
cd $out
cp ${build.squashfs} root.squashfs
cp ${build.kernel}/*zImage .
cp ${build.initialRamdisk}/initrd initrd
cp ${build.kernel}/dtbs/zynq-zc706.dtb .
ln -sv ${build.toplevel} toplevel
cp $qemuScriptPath qemu-script
chmod +x qemu-script
patchShebangs qemu-script
ls -ltrh
'';
```
---
### Author:  [@tobiasBora](https://discourse.nixos.org/u/tobiasBora)
#### Post date: [November 22, 2023, 10:07am UTC](https://discourse.nixos.org/t/build-uimage-instead-of-zimage/35855/2 "2023-11-22T10:07:14Z")
I am not at all a kernel expert, and I’m not even sure to know what you are trying to do, but a ` rg 'target = "uimage"' -i` in the nixpkgs folder points to [https://github.com/NixOS/nixpkgs/blob/3302bc3ddda5b1f72f7382b259d25856ed763a5e/lib/systems/platforms.nix#L66](https://github.com/NixOS/nixpkgs/blob/3302bc3ddda5b1f72f7382b259d25856ed763a5e/lib/systems/platforms.nix#L66) that contains stuff like:
```auto
pogoplug4 = {
linux-kernel = {
name = "pogoplug4";
baseConfig = "multi_v5_defconfig";
autoModules = false;
extraConfig = ''
# Ubi for the mtd
MTD_UBI y
UBIFS_FS y
UBIFS_FS_XATTR y
UBIFS_FS_ADVANCED_COMPR y
UBIFS_FS_LZO y
UBIFS_FS_ZLIB y
UBIFS_FS_DEBUG n
'';
makeFlags = ["LOADADDR=0x8000"];
target = "uImage";
# TODO reenable once manual-config's config actually builds a .dtb and this is checked to be working
#DTB = true;
};
gcc = {
arch = "armv5te";
};
};
```
which makes sense since when reading the code, you realize that `kernelConf` is set to `stdenv.hostPlatform.linux-kernel` (`host` being understood as the architecture running the kernel).
so doing an extrapolation with your code also containing `extraConfig`, my first try would be to do:
```auto
customKernel = pkgs.linux.override {
extraConfig = ''
OVERLAY_FS y
'';
# add this:
target = "uImage";
};
```
But I might be very wrong. Have you tried that before?
If not, you might want to give a try to this reading discussing how to override kernel options using `kernelPatches` [The \*correct\* way to override the latest kernel config - #7 by aszlig](https://discourse.nixos.org/t/the-correct-way-to-override-the-latest-kernel-config/533/7) and this discussion also seems related [Override kernel build dependencies - #3 by Skallwar](https://discourse.nixos.org/t/override-kernel-build-dependencies/24359/3)
---
### Author:  [@simpleboy0](https://discourse.nixos.org/u/simpleboy0)
#### Post date: [November 22, 2023, 6:26pm UTC](https://discourse.nixos.org/t/build-uimage-instead-of-zimage/35855/3 "2023-11-22T18:26:12Z")
Already tried to add `target = "uImage"`. Nothing seems to happen. Actually if I set any arbitrary values there, it was also not picked up. Maybe this is not the right way.
---
### Author:  [@tobiasBora](https://discourse.nixos.org/u/tobiasBora)
#### Post date: [November 22, 2023, 7:01pm UTC](https://discourse.nixos.org/t/build-uimage-instead-of-zimage/35855/4 "2023-11-22T19:01:03Z")
Uhm… Do you mean that `extraConfig` is also not considered, or this applies only to `target` ? What happens if you use something like:
```auto
boot.kernelPatches = [{ name="patch-uImage"; patch = null; target = "uImage"; }];
```
instead?
---
### Author:  [@simpleboy0](https://discourse.nixos.org/u/simpleboy0)
#### Post date: [November 22, 2023, 10:14pm UTC](https://discourse.nixos.org/t/build-uimage-instead-of-zimage/35855/6 "2023-11-22T22:14:29Z")
`extraConfig` was considered , just not the target. Tried the `boot.kernelPatches`. It rebuilds the kernel, though I do not know how to check for the `uImage` if it was really generated.