Improve support for old 16bit resume handlers.

Detect a non-standard CMOS shutdown code during post and run a
    separate resume handler.
Set aside space in the EBDA for the resume handler stack.
Add support for several of the code supported in bochs bios.

1 files changed, 81 insertions, 0 deletions

diff --git a/src/resume.c b/src/resume.c
new file mode 100644
index 00000000..559fa97d
--- /dev/null
+++ b/src/resume.c
@@ -0,0 +1,81 @@
+// Code for handling calls to "post" that are resume related.
+//
+// Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "util.h" // dprintf
+#include "ioport.h" // outb
+#include "pic.h" // eoi_pic2
+#include "biosvar.h" // struct bios_data_area_s
+
+// Reset DMA controller
+void
+init_dma()
+{
+    // first reset the DMA controllers
+    outb(0, PORT_DMA1_MASTER_CLEAR);
+    outb(0, PORT_DMA2_MASTER_CLEAR);
+
+    // then initialize the DMA controllers
+    outb(0xc0, PORT_DMA2_MODE_REG);
+    outb(0x00, PORT_DMA2_MASK_REG);
+}
+
+// Handler for post calls that look like a resume.
+void VISIBLE16
+handle_resume(u8 status)
+{
+    init_dma();
+
+    debug_serial_setup();
+    dprintf(1, "In resume (status=%d)\n", status);
+
+    switch (status) {
+    case 0x00:
+    case 0x09:
+    case 0x0d ... 0xff:
+        // Normal post - now that status has been cleared a reset will
+        // run regular boot code..
+        reset_vector();
+        break;
+
+    case 0x05:
+        // flush keyboard (issue EOI) and jump via 40h:0067h
+        eoi_pic2();
+        // NO BREAK
+    case 0x0a:
+        // resume execution by jump via 40h:0067h
+#define bda ((struct bios_data_area_s *)0)
+        asm volatile(
+            "movw %%ax, %%ds\n"
+            "ljmpw *%0\n"
+            : : "m"(bda->jump_ip), "a"(SEG_BDA)
+            );
+        break;
+
+    case 0x0b:
+        // resume execution via IRET via 40h:0067h
+        asm volatile(
+            "movw %%ax, %%ds\n"
+            "movw %0, %%sp\n"
+            "movw %1, %%ss\n"
+            "iretw\n"
+            : : "m"(bda->jump_ip), "m"(bda->jump_cs), "a"(SEG_BDA)
+            );
+        break;
+
+    case 0x0c:
+        // resume execution via RETF via 40h:0067h
+        asm volatile(
+            "movw %%ax, %%ds\n"
+            "movw %0, %%sp\n"
+            "movw %1, %%ss\n"
+            "lretw\n"
+            : : "m"(bda->jump_ip), "m"(bda->jump_cs), "a"(SEG_BDA)
+            );
+        break;
+    }
+
+    BX_PANIC("Unimplemented shutdown status: %02x\n", status);
+}