added linux swap header

diff --git a/palacios/src/devices/sym_swap.c b/palacios/src/devices/sym_swap.c
index f525db6..f2057f4 100644 (file)
--- a/palacios/src/devices/sym_swap.c
+++ b/palacios/src/devices/sym_swap.c
@@ -23,6 +23,28 @@
 
 #define SWAP_CAPACITY (150 * 1024 * 1024)
 
+
+/* This is the first page that linux writes to the swap area */
+/* Taken from Linux */
+union swap_header {
+    struct {
+       char reserved[PAGE_SIZE - 10];
+       char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
+    } magic;
+    struct {
+       char                    bootbits[1024]; /* Space for disklabel etc. */
+       uint32_t                version;
+       uint32_t                last_page;
+       uint32_t                nr_badpages;
+       unsigned char           sws_uuid[16];
+       unsigned char           sws_volume[16];
+       uint32_t                type;           // The index into the swap_map
+       uint32_t                padding[116];
+       //              uint32_t                padding[117];
+       uint32_t                badpages[1];
+    } info;
+};
+
 struct swap_state {
     
     struct vm_device * blk_dev;
@@ -82,6 +104,20 @@ static int swap_write(uint8_t * buf, int sector_count, uint64_t lba, void * priv
        PrintError("Swapping out length that is not a page multiple\n");
     }
 
+    if (offset == 0) {
+       // This is the swap header page 
+       union swap_header * hdr;
+       if (length != 4096) {
+           PrintError("Initializing Swap space by not writing page multiples. This sucks...\n");
+           return -1;
+       }
+
+       hdr = (union swap_header *)buf;
+       
+
+       PrintDebug("Swap Type=%d (magic=%s)\n", hdr->info.type, hdr->magic.magic);
+    }
+
     memcpy(swap->swap_space + offset, buf, length);
 
     swap->swapped_pages += (length / 4096);