fix(ci): use minimal kernel configs for both archs in QEMU tests

aarch64: defconfig (1973 options) -> allnoconfig + minimal virt config
armhf: already using vexpress_defconfig

Also fix build_initramfs.sh to use inline relative symlink creation
instead of gen_links.sh which uses absolute paths incompatible with
initramfs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Charliechen114514

.github/workflows/ci.yml

@@ -232,13 +232,15 @@ jobs:
           if [[ "${{ matrix.target }}" == "aarch64" ]]; then
             echo "arch=arm64" >> "$GITHUB_OUTPUT"
             echo "image=arch/arm64/boot/Image" >> "$GITHUB_OUTPUT"
-            echo "defconfig=defconfig" >> "$GITHUB_OUTPUT"
+            echo "defconfig=allnoconfig" >> "$GITHUB_OUTPUT"
             echo "cross=aarch64-linux-gnu-" >> "$GITHUB_OUTPUT"
+            echo "extra_config=configs/qemu-virt-aarch64.config" >> "$GITHUB_OUTPUT"
           else
             echo "arch=arm" >> "$GITHUB_OUTPUT"
             echo "image=arch/arm/boot/zImage" >> "$GITHUB_OUTPUT"
             echo "defconfig=vexpress_defconfig" >> "$GITHUB_OUTPUT"
             echo "cross=arm-none-linux-gnueabihf-" >> "$GITHUB_OUTPUT"
+            echo "extra_config=" >> "$GITHUB_OUTPUT"
           fi
 
       - name: Restore Linux kernel cache
@@ -256,6 +258,13 @@ jobs:
         run: |
           cd third_party/linux
           make ARCH=${{ steps.kernel.outputs.arch }} CROSS_COMPILE=${{ steps.kernel.outputs.cross }} ${{ steps.kernel.outputs.defconfig }}
+          if [[ -n "${{ steps.kernel.outputs.extra_config }}" ]]; then
+            while IFS='=' read -r key val; do
+              [[ -z "$key" || "$key" =~ ^# ]] && continue
+              ./scripts/config --enable "$key"
+            done < "${{ github.workspace }}/${{ steps.kernel.outputs.extra_config }}"
+            make ARCH=${{ steps.kernel.outputs.arch }} CROSS_COMPILE=${{ steps.kernel.outputs.cross }} olddefconfig
+          fi
           make ARCH=${{ steps.kernel.outputs.arch }} CROSS_COMPILE=${{ steps.kernel.outputs.cross }} -j$(nproc)
 
       - name: Save Linux kernel cache

configs/qemu-virt-aarch64.config

@@ -0,0 +1,52 @@
+# Minimal Linux config for QEMU virt machine (aarch64)
+# Usage: make ARCH=arm64 allnoconfig && make ARCH=arm64 qemu-virt-aarch64.config
+# Or:   scripts/config --file .config --enable <option> && make olddefconfig
+
+# Architecture
+CONFIG_ARM64=y
+
+# Platform - QEMU virt
+CONFIG_ARCH_VEXPRESS=y
+CONFIG_PCI=y
+CONFIG_PCI_HOST_GENERIC=y
+
+# SMP
+CONFIG_SMP=y
+CONFIG_NR_CPUS=4
+
+# Serial console (PL011 on QEMU virt)
+CONFIG_TTY=y
+CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
+CONFIG_CONSOLE_TRANSLATIONS=y
+
+# Initramfs
+CONFIG_BLK_DEV_INITRD=y
+
+# Filesystems needed for basic boot
+CONFIG_PROC_FS=y
+CONFIG_SYSFS=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_TMPFS=y
+
+# devtmpfs auto-mount requires these
+CONFIG_INOTIFY_USER=y
+CONFIG_FUTEX=y
+
+# Required for PID 1 / init
+CONFIG_BINFMT_ELF=y
+CONFIG_BINFMT_SCRIPT=y
+
+# Printk for console output
+CONFIG_PRINTK=y
+
+# Block layer (minimal)
+CONFIG_BLOCK=y
+
+# Basic kernel features
+CONFIG_MULTIUSER=y
+CONFIG_SYSVIPC=y
+
+# Power management - not needed for QEMU but harmless
+# Keep minimal