[Qemu-devel] [PATCH v8 0/2] aarch64: Allow -kernel option to take a gzip-compressed kernel

[Qemu-devel] [PATCH v8 0/2] aarch64: Allow -kernel option to take a gzip-compressed kernel

[Richard W.M. Jones]

Changes since v7:

 - Rebase against current head & retest.

 - Don't use `allow_compressed_kernel' boolean, but use arm_feature test
   at point of use instead.

 - Added Reviewed-by tags (thanks Peter Crosthwaite).

Rich.

[Qemu-devel] [PATCH v8 1/2] loader: Add load_image_gzipped function.

[Richard W.M. Jones]

As the name suggests this lets you load a ROM/disk image that is
gzipped.  It is uncompressed before storing it in guest memory.

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---
 hw/core/loader.c    | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/loader.h |  1 +
 2 files changed, 49 insertions(+)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 2bf6b8f..83136e8 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -577,6 +577,54 @@ int load_ramdisk(const char *filename, hwaddr addr, uint64_t max_sz)
     return load_uboot_image(filename, NULL, &addr, NULL, IH_TYPE_RAMDISK);
 }
 
+/* This simply prevents g_malloc in the function below from allocating
+ * a huge amount of memory, by placing a limit on the maximum
+ * uncompressed image size that load_image_gzipped will read.
+ */
+#define LOAD_IMAGE_MAX_GUNZIP_BYTES (256 << 20)
+
+/* Load a gzip-compressed kernel. */
+int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz)
+{
+    uint8_t *compressed_data = NULL;
+    uint8_t *data = NULL;
+    gsize len;
+    ssize_t bytes;
+    int ret = -1;
+
+    if (!g_file_get_contents(filename, (char **) &compressed_data, &len,
+                             NULL)) {
+        goto out;
+    }
+
+    /* Is it a gzip-compressed file? */
+    if (len < 2 ||
+        compressed_data[0] != 0x1f ||
+        compressed_data[1] != 0x8b ) {
+        goto out;
+    }
+
+    if (max_sz > LOAD_IMAGE_MAX_GUNZIP_BYTES) {
+        max_sz = LOAD_IMAGE_MAX_GUNZIP_BYTES;
+    }
+
+    data = g_malloc(max_sz);
+    bytes = gunzip(data, max_sz, compressed_data, len);
+    if (bytes < 0) {
+        fprintf(stderr, "%s: unable to decompress gzipped kernel file\n",
+                filename);
+        goto out;
+    }
+
+    rom_add_blob_fixed(filename, data, bytes, addr);
+    ret = bytes;
+
+ out:
+    g_free(compressed_data);
+    g_free(data);
+    return ret;
+}
+
 /*
  * Functions for reboot-persistent memory regions.
  *  - used for vga bios and option roms.
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 796cbf9..00c9117 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -15,6 +15,7 @@ int get_image_size(const char *filename);
 int load_image(const char *filename, uint8_t *addr); /* deprecated */
 int load_image_targphys(const char *filename, hwaddr,
                         uint64_t max_sz);
+int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz);
 
 #define ELF_LOAD_FAILED       -1
 #define ELF_LOAD_NOT_ELF      -2
-- 
2.0.4

[Qemu-devel] [PATCH v8 2/2] aarch64: Allow -kernel option to take a gzip-compressed kernel.

[Richard W.M. Jones]

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>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---
 hw/arm/boot.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 1241761..e32f2f4 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -514,6 +514,13 @@ 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 (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && 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

Re: [Qemu-devel] [PATCH v8 0/2] aarch64: Allow -kernel option to take a gzip-compressed kernel

[Peter Maydell]

On 12 August 2014 09:14, Richard W.M. Jones <rjones@redhat.com> wrote:
> Changes since v7:
>
>  - Rebase against current head & retest.
>
>  - Don't use `allow_compressed_kernel' boolean, but use arm_feature test
>    at point of use instead.
>
>  - Added Reviewed-by tags (thanks Peter Crosthwaite).

Thanks; applied to target-arm.next.

-- PMM