[Qemu-devel] [PATCH v5 2/2] aarch64: Allow -kernel option to take a gzip-compressed kernel.

["Richard W.M. Jones" <rjones@redhat.com>]

On aarch64 it is the bootloader's job to uncompress the kernel.  UEFI
and u-boot bootloaders do this automatically when the kernel is
gzip-compressed.

However the qemu -kernel option does not do this.  The following
command does not work:

  qemu-system-aarch64 [...] -kernel /boot/vmlinuz

because it tries to execute the gzip-compressed data.

This commit lets gzip-compressed kernels be uncompressed
transparently.

Currently this is only done when emulating aarch64.

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
---
 hw/arm/boot.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 3d1f4a2..1d541db 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -444,6 +444,7 @@ static void do_cpu_reset(void *opaque)
 void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
 {
     CPUState *cs = CPU(cpu);
+    int allow_compressed_kernels = 0;
     int kernel_size;
     int initrd_size;
     int is_linux = 0;
@@ -465,6 +466,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
         primary_loader = bootloader_aarch64;
         kernel_load_offset = KERNEL64_LOAD_ADDR;
         elf_machine = EM_AARCH64;
+        allow_compressed_kernels = 1;
     } else {
         primary_loader = bootloader;
         kernel_load_offset = KERNEL_LOAD_ADDR;
@@ -510,6 +512,13 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
         kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
                                   &is_linux);
     }
+    /* On aarch64, it's the bootloader's job to uncompress the kernel. */
+    if (allow_compressed_kernels && kernel_size < 0) {
+        entry = info->loader_start + kernel_load_offset;
+        kernel_size = load_image_gzipped(info->kernel_filename, entry,
+                                         info->ram_size - kernel_load_offset);
+        is_linux = 1;
+    }
     if (kernel_size < 0) {
         entry = info->loader_start + kernel_load_offset;
         kernel_size = load_image_targphys(info->kernel_filename, entry,
-- 
2.0.4