Allow optionroms and "low mem" to share space.

Allow both optionroms and "low mem" allocations to use the e-segment.
(Space is allocated on a "first come, first serve" basis).  This
allows more flexibility in resource assignment.

Also, allow the "low mem" area to use a full 64K.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 58 insertions, 14 deletions

diff --git a/src/pmm.c b/src/pmm.c
index 1648bf24..facea6bf 100644
--- a/src/pmm.c
+++ b/src/pmm.c
@@ -162,17 +162,66 @@ findLast(struct zone_s *zone)
 
 
 /****************************************************************
- * Setup
+ * 0xc0000-0xf0000 management
  ****************************************************************/
 
-// Return start of code in 0xc0000-0xf0000 space.
+static u32 RomEnd = BUILD_ROM_START;
+static struct allocinfo_s *RomBase;
+
+#define OPROM_HEADER_RESERVE 16
+
+// Return maximum address of read/writable "low mem" space.
 static inline u32 lowmemend(void) {
     extern u8 code32flat_start[], code32init_end[];
     u32 end = CONFIG_RELOCATE_INIT ? (u32)code32init_end : (u32)code32flat_start;
     return end > BUILD_BIOS_ADDR ? BUILD_BIOS_ADDR : end;
 }
 
-#define OPROM_HEADER_RESERVE 16
+// Return the memory position up to which roms may be located.
+u32
+rom_get_top(void)
+{
+    return ALIGN_DOWN((u32)RomBase->allocend - OPROM_HEADER_RESERVE
+                      , OPTION_ROM_ALIGN);
+}
+
+// Return the end of the last deployed rom.
+u32
+rom_get_last(void)
+{
+    return RomEnd;
+}
+
+// Request space for an optionrom in 0xc0000-0xf0000 area.
+struct rom_header *
+rom_reserve(u32 size)
+{
+    u32 newend = ALIGN(RomEnd + size, OPTION_ROM_ALIGN) + OPROM_HEADER_RESERVE;
+    if (newend > (u32)RomBase->allocend)
+        return NULL;
+    if (newend < (u32)_datalow_base + OPROM_HEADER_RESERVE)
+        newend = (u32)_datalow_base + OPROM_HEADER_RESERVE;
+    RomBase->data = RomBase->dataend = (void*)newend;
+    return (void*)RomEnd;
+}
+
+// Confirm space as in use by an optionrom.
+int
+rom_confirm(u32 size)
+{
+    void *new = rom_reserve(size);
+    if (!new) {
+        warn_noalloc();
+        return -1;
+    }
+    RomEnd = ALIGN(RomEnd + size, OPTION_ROM_ALIGN);
+    return 0;
+}
+
+
+/****************************************************************
+ * Setup
+ ****************************************************************/
 
 void
 malloc_setup(void)
@@ -204,9 +253,8 @@ malloc_setup(void)
     // Populate other regions
     addSpace(&ZoneTmpLow, (void*)BUILD_STACK_ADDR, (void*)BUILD_EBDA_MINIMUM);
     addSpace(&ZoneFSeg, BiosTableSpace, &BiosTableSpace[CONFIG_MAX_BIOSTABLE]);
-    u32 lowend = lowmemend();
-    RomTop = ALIGN_DOWN(lowend-BUILD_LOWMEM_SIZE, OPTION_ROM_ALIGN);
-    addSpace(&ZoneLow, (void*)RomTop + OPROM_HEADER_RESERVE, (void*)lowend);
+    addSpace(&ZoneLow, _datalow_base + OPROM_HEADER_RESERVE, (void*)lowmemend());
+    RomBase = findLast(&ZoneLow);
     if (highram) {
         addSpace(&ZoneHigh, (void*)highram
                  , (void*)highram + CONFIG_MAX_HIGHTABLE);
@@ -246,14 +294,10 @@ malloc_finalize(void)
 
     // Place an optionrom signature around used low mem area.
     struct allocinfo_s *info = findLast(&ZoneLow);
-    u32 base = BUILD_BIOS_ADDR;
-    if (info && info->allocend < (void*)BUILD_BIOS_ADDR) {
-        base = ALIGN_DOWN((u32)info->allocend - OPROM_HEADER_RESERVE
-                          , OPTION_ROM_ALIGN);
-        struct rom_header *dummyrom = (void*)base;
-        dummyrom->signature = OPTION_ROM_SIGNATURE;
-        dummyrom->size = (BUILD_BIOS_ADDR - base) / 512;
-    }
+    u32 base = rom_get_top();
+    struct rom_header *dummyrom = (void*)base;
+    dummyrom->signature = OPTION_ROM_SIGNATURE;
+    dummyrom->size = (BUILD_BIOS_ADDR - base) / 512;
     memset((void*)RomEnd, 0, base-RomEnd);
     dprintf(1, "Space available for UMB: %08x-%08x\n", RomEnd, base);