X86: Start setting up the real mode data structure.

--HG--
extra : convert_revision : ba6d4939d4d58da5586655c83f1617f47dc7e359

src/arch/x86/linux/system.cc

@@ -55,9 +55,11 @@
  * Authors: Gabe Black
  */
 
+#include "arch/x86/intregs.hh"
 #include "arch/x86/linux/system.hh"
 #include "arch/vtophys.hh"
 #include "base/trace.hh"
+#include "cpu/thread_context.hh"
 #include "mem/physical.hh"
 #include "params/LinuxX86System.hh"
 
@@ -78,7 +80,132 @@ void
 LinuxX86System::startup()
 {
     X86System::startup();
-    //Build the real mode data structure.
+
+    // The location of the real mode data structure.
+    const Addr realModeData = 0x90200;
+
+    // A port to write to memory.
+    FunctionalPort * physPort = threadContexts[0]->getPhysPort();
+
+    /*
+     * Deal with the command line stuff.
+     */
+
+    // A buffer to store the command line.
+    const Addr commandLineBuff = 0x90000;
+    // A pointer to the commandLineBuff stored in the real mode data.
+    const Addr commandLinePointer = realModeData + 0x228;
+
+    if (commandLine.length() + 1 > realModeData - commandLineBuff)
+        panic("Command line \"%s\" is longer than %d characters.\n",
+                commandLine, realModeData - commandLineBuff - 1);
+    physPort->writeBlob(commandLineBuff,
+            (uint8_t *)commandLine.c_str(), commandLine.length() + 1);
+
+    // Generate a pointer of the right size and endianness to put into
+    // commandLinePointer.
+    uint32_t guestCommandLineBuff =
+        X86ISA::htog((uint32_t)commandLineBuff);
+    physPort->writeBlob(commandLinePointer,
+            (uint8_t *)&guestCommandLineBuff, sizeof(guestCommandLineBuff));
+
+    /*
+     * Screen Info.
+     */
+
+    // We'll skip on this for now because it's only needed for framebuffers,
+    // something we don't support at the moment.
+
+    /*
+     * EDID info
+     */
+
+    // Skipping for now.
+
+    /*
+     * Saved video mode
+     */
+
+    // Skipping for now.
+
+    /*
+     * Loader type.
+     */
+
+    // Skipping for now.
+
+    /*
+     * E820 memory map
+     */
+
+    // A pointer to the number of E820 entries there are.
+    const Addr e820MapNrPointer = realModeData + 0x1e8;
+
+    // A pointer to the buffer for E820 entries.
+    const Addr e820MapPointer = realModeData + 0x2d0;
+
+    struct e820Entry
+    {
+        Addr addr;
+        Addr size;
+        uint32_t type;
+    };
+
+    // The size is computed this way to ensure no padding sneaks in.
+    int e820EntrySize =
+        sizeof(e820Entry().addr) +
+        sizeof(e820Entry().size) +
+        sizeof(e820Entry().type);
+
+    // I'm not sure what these should actually be. On a real machine they
+    // would be generated by the BIOS, and they need to reflect the regions
+    // which are actually available/reserved. These values are copied from
+    // my development machine.
+    e820Entry e820Map[] = {
+        {ULL(0x0), ULL(0x9d400), 1},
+        {ULL(0x9d400), ULL(0xa0000) - ULL(0x9d400), 2},
+        {ULL(0xe8000), ULL(0x100000) - ULL(0xe8000), 2},
+        {ULL(0x100000), ULL(0xcfff9300) - ULL(0x100000), 1},
+        {ULL(0xcfff9300), ULL(0xd0000000) - ULL(0xcfff9300), 2},
+        {ULL(0xfec00000), ULL(0x100000000) - ULL(0xfec00000), 2}
+    };
+
+    uint8_t e820Nr = sizeof(e820Map) / sizeof(e820Entry);
+
+    // Make sure the number of entries isn't bigger than what the kernel
+    // would be capable of providing.
+    assert(e820Nr <= 128);
+
+    uint8_t guestE820Nr = X86ISA::htog(e820Nr);
+    physPort->writeBlob(e820MapNrPointer,
+            (uint8_t *)&guestE820Nr, sizeof(guestE820Nr));
+
+    for (int i = 0; i < e820Nr; i++) {
+        e820Entry guestE820Entry;
+        guestE820Entry.addr = X86ISA::htog(e820Map[i].addr);
+        guestE820Entry.size = X86ISA::htog(e820Map[i].size);
+        guestE820Entry.type = X86ISA::htog(e820Map[i].type);
+        physPort->writeBlob(e820MapPointer + e820EntrySize * i,
+                (uint8_t *)&guestE820Entry.addr,
+                sizeof(guestE820Entry.addr));
+        physPort->writeBlob(
+                e820MapPointer + e820EntrySize * i +
+                    sizeof(guestE820Entry.addr),
+                (uint8_t *)&guestE820Entry.size,
+                sizeof(guestE820Entry.size));
+        physPort->writeBlob(
+                e820MapPointer + e820EntrySize * i +
+                    sizeof(guestE820Entry.addr) +
+                    sizeof(guestE820Entry.size),
+                (uint8_t *)&guestE820Entry.type,
+                sizeof(guestE820Entry.type));
+    }
+
+    /*
+     * Pass the location of the real mode data structure to the kernel
+     * using register %esi. We'll use %rsi which should be equivalent.
+     */
+    threadContexts[0]->setIntReg(INTREG_RSI, realModeData);
 }
 
 LinuxX86System *