xv6.patch

diff --git a/Makefile b/Makefile
index 20cb884..e2d9196 100644
--- a/Makefile
+++ b/Makefile
@@ -121,8 +121,8 @@ kernel: $(OBJS) entry.o entryother initcode kernel.ld
 # great for testing the kernel on real hardware without
 # needing a scratch disk.
 MEMFSOBJS = $(filter-out ide.o,$(OBJS)) memide.o
-kernelmemfs: $(MEMFSOBJS) entry.o entryother initcode fs.img
-   $(LD) $(LDFLAGS) -Ttext 0x100000 -e main -o kernelmemfs entry.o  $(MEMFSOBJS) -b binary initcode entryother fs.img
+kernelmemfs: $(MEMFSOBJS) entry.o entryother initcode kernel.ld fs.img
+   $(LD) $(LDFLAGS) -T kernel.ld -o kernelmemfs entry.o  $(MEMFSOBJS) -b binary initcode entryother fs.img
    $(OBJDUMP) -S kernelmemfs > kernelmemfs.asm
    $(OBJDUMP) -t kernelmemfs | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernelmemfs.sym

diff --git a/kernel.ld b/kernel.ld
index e24c860..a02d5b4 100644
--- a/kernel.ld
+++ b/kernel.ld
@@ -3,7 +3,7 @@

 OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
 OUTPUT_ARCH(i386)
-ENTRY(_start)
+ENTRY(entry)

 SECTIONS
 {
diff --git a/vm.c b/vm.c
index 4cffb58..2f4ba3e 100644
--- a/vm.c
+++ b/vm.c
@@ -32,6 +32,10 @@ seginit(void)
   c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);

   lgdt(c->gdt, sizeof(c->gdt));
+
+  loadcs(SEG_KCODE << 3);
+  loadds(SEG_KDATA << 3);
+  loades(SEG_KDATA << 3);
   loadgs(SEG_KCPU << 3);

   // Initialize cpu-local storage.
diff --git a/x86.h b/x86.h
index 3949900..7d4bcce 100644
--- a/x86.h
+++ b/x86.h
@@ -99,6 +99,22 @@ readeflags(void)
   return eflags;
 }

+#define loadcs(v)                               \
+  asm volatile("ljmp %0, $set_cs\n"             \
+               "set_cs:" : : "n" (v));
+
+static inline void
+loadds(ushort v)
+{
+  asm volatile("movw %0, %%ds" : : "r" (v));
+}
+
+static inline void
+loades(ushort v)
+{
+  asm volatile("movw %0, %%es" : : "r" (v));
+}
+
 static inline void
 loadgs(ushort v)
 {