Cleaner memory map; avoid < 64K; handle older kernels

Clean up the memory map by making the startup info part of the reloc
segment; this also allows it to be easily prepopulated.

Avoid using < 64K by putting the reloc between the setup and cmdline,
with proper guarding for overflow.

Handle older kernel protocols, and zImage kernels.

1 files changed, 17 insertions, 11 deletions

diff --git a/reloc/reloc_linux.c b/reloc/reloc_linux.c
index 5849c54..79655c1 100644
--- a/reloc/reloc_linux.c
+++ b/reloc/reloc_linux.c
@@ -158,30 +158,36 @@ static int place_initrd(void)
 	return probe_memory_88();
 }
 
+extern char _end[];
+/* This structure is hacked by the installer */
+static const struct startup_info startup_info
+__attribute__((section(".startupinfo"))) =
+{
+	.reloc_size = (uint32_t)&_end,
+};
+
 int main(void)
 {
-	extern struct startup_info _start[]; /* Cute hack, eh? */
-	struct startup_info *info = _start - 1;
-	struct setup_header *hdr = (void *)(info->setup_addr + 0x1f1);
+	struct setup_header *hdr = (void *)(startup_info.setup_addr + 0x1f1);
 
-	if (info->rd_len) {
-		initrd_len = info->rd_len;
-		max_addr   = info->rd_maxaddr;
+	if (startup_info.rd_len) {
+		initrd_len = startup_info.rd_len;
+		max_addr   = startup_info.rd_maxaddr;
 
 		if (place_initrd())
 			return -1;
 
 		/* Move the initrd into place */
 		printf("Moving initrd: 0x%08x -> 0x%08x (0x%08x bytes)\n",
-		       info->rd_addr, initrd_addr, info->rd_len);
+		       startup_info.rd_addr, initrd_addr, startup_info.rd_len);
 
-		memmove((void *)initrd_addr, (void *)info->rd_addr,
-			info->rd_len);
+		memmove((void *)initrd_addr, (void *)startup_info.rd_addr,
+			startup_info.rd_len);
 		
 		hdr->ramdisk_image = initrd_addr;
 	}
 
-	jump_to_kernel(info->setup_addr >> 4,
-		       info->cmdline_addr - info->setup_addr);
+	jump_to_kernel(startup_info.setup_addr >> 4,
+		       startup_info.cmdline_addr - startup_info.setup_addr);
 	return -1;		/* Shouldn't return... */
 }