[Xen-devel] [PATCH] readnote: Add bzImage kernel support

[Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx>]

Add the check of bzImage kernel and make it work
with RHEL 6 bzipped kernels

Signed-off-by: Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx>

diff -r d690c7e896a2 -r ec8e99606fbe tools/xcutils/readnotes.c
--- a/tools/xcutils/readnotes.c Thu Apr 05 11:06:03 2012 +0100
+++ b/tools/xcutils/readnotes.c Thu Apr 26 10:57:09 2012 +0800
@@ -18,6 +18,48 @@
 
 static xc_interface *xch;
 
+/* According to the implemation of xc_dom_probe_bzimage_kernel() function */
+/* We add support of bzImage kernel */
+/* Copied from tools/libxc/xc_doom_bzImageloader.c */
+struct setup_header {
+       uint8_t  _pad0[0x1f1];  /* skip uninteresting stuff */
+       uint8_t  setup_sects;
+       uint16_t root_flags;
+       uint32_t syssize;
+       uint16_t ram_size;
+       uint16_t vid_mode;
+       uint16_t root_dev;
+       uint16_t boot_flag;
+       uint16_t jump;
+       uint32_t header;
+#define HDR_MAGIC  "HdrS"
+#define HDR_MAGIC_SZ 4
+       uint16_t version;
+#define VERSION(h,l) (((h)<<8) | (l))
+       uint32_t realmode_swtch;
+       uint16_t start_sys;
+       uint16_t kernel_version;
+       uint8_t  type_of_loader;
+       uint8_t  loadflags;
+       uint16_t setup_move_size;
+       uint32_t code32_start;
+       uint32_t ramdisk_image;
+       uint32_t ramdisk_size;
+       uint32_t bootsect_kludge;
+       uint16_t heap_end_ptr;
+       uint16_t _pad1;
+       uint32_t cmd_line_ptr;
+       uint32_t initrd_addr_max;
+       uint32_t kernel_alignment;
+       uint8_t  relocatable_kernel;
+       uint8_t  _pad2[3];
+       uint32_t cmdline_size;
+       uint32_t hardware_subarch;
+       uint64_t hardware_subarch_data;
+       uint32_t payload_offset;
+       uint32_t payload_length;
+} __attribute__((packed));
+
 static void print_string_note(const char *prefix, struct elf_binary *elf,
                              const elf_note *note)
 {
@@ -131,6 +173,9 @@ int main(int argc, char **argv)
        const elf_shdr *shdr;
        int notes_found = 0;
 
+       struct setup_header *hdr;
+       uint64_t payload_offset, payload_length;
+
        if (argc != 2)
        {
                fprintf(stderr, "Usage: readnotes <elfimage>\n");
@@ -159,6 +204,27 @@ int main(int argc, char **argv)
                fprintf(stderr, "Unable to map %s: %s\n", f, strerror(errno));
                return 1;
        }
+       
+       /* Check the magic of bzImage kernel */
+       hdr = (struct setup_header *)image;
+       if ( memcmp(&hdr->header, HDR_MAGIC, HDR_MAGIC_SZ) == 0 )
+       {
+               if ( hdr->version < VERSION(2,8) )
+               {
+                       printf("%s: boot protocol too old (%04x)", 
__FUNCTION__, hdr->version);
+                       return 1;
+               }
+
+               /* upcast to 64 bits to avoid overflow */
+               /* setup_sects is u8 and so cannot overflow */
+               payload_offset = (hdr->setup_sects + 1) * 512;
+               payload_offset += hdr->payload_offset;
+               payload_length = hdr->payload_length;
+
+               image = image + payload_offset;
+               st.st_size = payload_length;
+       }
+       
        size = st.st_size;
 
        usize = xc_dom_check_gzip(xch, image, st.st_size);

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