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

["Alex Bennée" <alex.bennee@linaro.org>]

Richard W.M. Jones writes:

> 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,

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée