[Qemu-devel] [PATCH v2 6/6] load_linux: change kernel header size allocation

[liguang]

it's not necessary to alloc 8K bytes for kernel
header, 0.5K is enough.

Signed-off-by: liguang <lig.f...@cn.fujitsu.com>
---
 hw/pc.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 30b3262..4f78d4f 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -637,6 +637,9 @@ static long get_file_size(FILE *f)
     return size;
 }
 
+#define HEADER_SIZE 0x200
+#define HEADER_SIGNATURE 0x53726448
+
 static void load_linux(void *fw_cfg,
                        const char *kernel_filename,
                        const char *initrd_filename,
@@ -646,7 +649,7 @@ static void load_linux(void *fw_cfg,
     uint16_t protocol;
     int setup_size, kernel_size, initrd_size = 0, cmdline_size;
     uint32_t initrd_max;
-    uint8_t header[8192], *setup, *kernel, *initrd_data;
+    uint8_t header[HEADER_SIZE], *setup, *kernel, *initrd_data;
     hwaddr real_addr, prot_addr, cmdline_addr, initrd_addr = 0;
     FILE *f;
     char *vmode;
@@ -667,8 +670,7 @@ static void load_linux(void *fw_cfg,
                 strerror(errno));
         exit(1);
     }
-    if (fread(header, 1, MIN(ARRAY_SIZE(header), kernel_size), f) !=
-        MIN(ARRAY_SIZE(header), kernel_size)) {
+    if (fread(header, 1, HEADER_SIZE, f) <= 0) {
         fprintf(stderr, "qemu: could not load kernel '%s': %s\n",
                 kernel_filename, strerror(errno));
         exit(1);
@@ -678,9 +680,9 @@ static void load_linux(void *fw_cfg,
 #if 0
     fprintf(stderr, "header magic: %#x\n", ldl_p(header+0x202));
 #endif
-    if (ldl_p(header+0x202) == 0x53726448)
-        protocol = lduw_p(header+0x206);
-    else {
+    if (ldl_p(header + 0x202) == HEADER_SIGNATURE) {
+        protocol = lduw_p(header + 0x206);
+    } else {
         /* This looks like a multiboot kernel. If it is, let's stop
            treating it like a Linux kernel. */
         if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
-- 
1.7.2.5