Checkpoint: add printf() for debugging, remove query of E881 (seems

to hang some systems), move E820 table to conventional memory
(sized dynamically), use BIOS memory pointer to determine where in
DOS memory to put our routine.

1 files changed, 64 insertions, 12 deletions

diff --git a/memdisk/setup.c b/memdisk/setup.c
index 64d66ec2..196f33bb 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -32,7 +32,6 @@ struct patch_area {
   uint32_t disksize;
   uint32_t diskbuf;
 
-  uint32_t e820table;
   uint32_t mem1mb;
   uint32_t mem16mb;
   uint32_t memint1588;
@@ -88,7 +87,7 @@ wrz_16(uint32_t addr, uint16_t data)
   asm volatile("movw %0,%%fs:%1" :: "ri" (data), "m" (*(uint16_t *)addr));
 }
 static inline void
-wrz_32(uint32_t addr, uint16_t data)
+wrz_32(uint32_t addr, uint32_t data)
 {
   asm volatile("movl %0,%%fs:%1" :: "ri" (data), "m" (*(uint32_t *)addr));
 }
@@ -173,41 +172,70 @@ const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
 }
 
 /*
+ * Jump here if all hope is gone...
+ */
+void __attribute__((noreturn)) die(void)
+{
+  asm volatile("sti");
+  for(;;)
+    asm volatile("hlt");
+}
+
+/*
  * Actual setup routine
  * Returns the drive number (which is then passed in %dl to the
  * called routine.)
  */
 uint32_t setup(void)
 {
-  unsigned int size = (int) &_binary_memdisk_bin_size;
+  unsigned int bin_size = (int) &_binary_memdisk_bin_size;
   struct memdisk_header *hptr;
   struct patch_area *pptr;
   uint16_t driverseg;
   uint32_t driverptr, driveraddr;
+  uint16_t dosmem_k;
+  uint32_t stddosmem;
   uint8_t driveno = 0;
   uint8_t status;
   uint16_t exitcode;
   const struct geometry *geometry;
+  int total_size;
 
   /* Show signs of life */
-  puts("Memdisk: hello, world!\n");
+  puts("Memdisk: Hello, World!\n");
+
+  if ( !shdr->ramdisk_image || !shdr->ramdisk_size ) {
+    puts("MEMDISK: No ramdisk image specified!\n");
+    die();
+  }
+
+  printf("Test of simple printf...\n");
+  printf("Ramdisk at 0x%08x, length 0x%08x\n",
+	 shdr->ramdisk_image, shdr->ramdisk_size);
 
-  for(;;);
+  /* Reserve the ramdisk memory */
+  insertrange(shdr->ramdisk_image, shdr->ramdisk_size, 2);
 
   geometry = get_disk_image_geometry(shdr->ramdisk_image, shdr->ramdisk_size);
 
   get_mem();
   parse_mem();
 
+  printf("dos_mem  = %#10x (%u K)\n"
+	 "low_mem  = %#10x (%u K)\n"
+	 "high_mem = %#10x (%u K)\n",
+	 dos_mem, dos_mem >> 10,
+	 low_mem, low_mem >> 10,
+	 high_mem, high_mem >> 10);
+
   /* Figure out where it needs to go */
   hptr = (struct memdisk_header *) &_binary_memdisk_bin_start;
   pptr = (struct patch_area *)(_binary_memdisk_bin_start + hptr->patch_offs);
 
-  if ( hptr->total_size > dos_mem ) {
-    /* Badness... */
-  }
+  dosmem_k = rdz_16(BIOS_BASEMEM);
+  pptr->olddosmem = dosmem_k;
+  stddosmem = dosmem_k << 10;
 
-  pptr->olddosmem = rdz_16(BIOS_BASEMEM);
   pptr->driveno   = geometry->driveno;
   pptr->drivetype = geometry->type;
   pptr->cylinders = geometry->c;
@@ -216,9 +244,25 @@ uint32_t setup(void)
   pptr->disksize  = geometry->sectors;
   pptr->diskbuf   = shdr->ramdisk_image;
 
-  driveraddr  = dos_mem - hptr->total_size;
+  /* The size is given by hptr->total_size plus the size of the
+     E820 map -- 12 bytes per range; we may need as many as
+     2 additional ranges plus the terminating range, over what
+     nranges currently show. */
+
+  total_size = hptr->total_size + (nranges+3)*12;
+  printf("Total size needed = %u bytes\n", total_size);
+
+  if ( total_size > dos_mem ) {
+    puts("MEMDISK: Insufficient low memory\n");
+    die();
+  }
+
+  driveraddr  = stddosmem - total_size;
   driveraddr &= ~0x3FF;
 
+  printf("Old dos memory at 0x%05x (map says 0x%05x), loading at 0x%05x\n",
+	 stddosmem, dos_mem, driveraddr);
+
   /* Reserve this range of memory */
   insertrange(driveraddr, dos_mem-driveraddr, 2);
   parse_mem();
@@ -238,12 +282,19 @@ uint32_t setup(void)
   /* Claim the memory and copy the driver into place */
   wrz_16(BIOS_BASEMEM, dos_mem >> 10);
 
+  /* Copy driver followed by E820 table */
   asm volatile("pushw %%es ; "
 	       "movw %0,%%es ; "
+	       "cld ; "
+	       "rep ; movsl %%ds:(%%si), %%es:(%%di) ; "
+	       "movw %2,%%cx ; "
+	       "movw %1,%%si ; "
 	       "rep ; movsl %%ds:(%%si), %%es:(%%di) ; "
 	       "popw %%es"
 	       :: "r" (driverseg),
-	       "c" (size >> 2),
+	       "g" ((uint16_t)((nranges+1)*3)), /* 3 dwords/range */
+	       "g" ((uint16_t)ranges),
+	       "c" (bin_size >> 2),
 	       "S" (&_binary_memdisk_bin_start),
 	       "D" (0));
 
@@ -266,7 +317,8 @@ uint32_t setup(void)
 	       : "ebx", "ecx", "edx", "esi", "edi", "ebp");
 
   if ( status ) {
-    /* Badness... */
+    puts("MEMDISK: Failed to load new boot sector\n");
+    die();
   }
   
   /* On return the assembly code will jump to the boot vector */