map two pages of Sysmap rather than 1.

fixes ramdisk loading problem (kernel > 4M).
some comments.

diff --git a/sys/arch/i386/i386/locore.s b/sys/arch/i386/i386/locore.s
index 12e6594..a534230 100644 (file)
--- a/sys/arch/i386/i386/locore.s
+++ b/sys/arch/i386/i386/locore.s
@@ -189,7 +189,7 @@ tmpstk:
        .text
        .globl  start
        .globl  _kernel_text
-       _kernel_text = start
+       _kernel_text = KERNTEXTOFF
 start: movw    $0x1234,0x472                   # warm boot
 
        /*
@@ -491,27 +491,25 @@ try586:   /* Use the `cpuid' instruction. */
        stosl
 
        /* Find end of kernel image. */
-       movl    $RELOC(_end),%edi
+       movl    $RELOC(_end),%esi
 #if defined(DDB) && !defined(SYMTAB_SPACE)
        /* Save the symbols (if loaded). */
        movl    RELOC(_esym),%eax
        testl   %eax,%eax
        jz      1f
        subl    $KERNBASE,%eax
-       movl    %eax,%edi
+       movl    %eax,%esi
 1:
 #endif
 
        /* Calculate where to start the bootstrap tables. */
-       movl    %edi,%esi                       # edi = esym ? esym : end
-       addl    $PGOFSET,%esi                   # page align up
-       andl    $~PGOFSET,%esi
+       addl    $PGOFSET, %esi                  # page align up
+       andl    $~PGOFSET, %esi
 
        /* Clear memory for bootstrap tables. */
-       leal    (TABLESIZE)(%esi),%ecx          # end of tables
-       subl    %edi,%ecx                       # size of tables
-       shrl    $2,%ecx
-       xorl    %eax,%eax
+       movl    %esi, %edi
+       movl    $((TABLESIZE + 3) >> 2), %ecx   # size of tables
+       xorl    %eax, %eax
        cld
        rep
        stosl
@@ -566,18 +564,29 @@ try586:   /* Use the `cpuid' instruction. */
 
 /*
  * Construct a page table directory.
+ *
+ * Install a PDE for temporary double map of kernel text.
+ * Maps two pages, in case the kernel is larger than 4M.
+ * XXX: should the number of pages to map be decided at run-time?
+ */
+       leal    (SYSMAP+PG_V|PG_KW)(%esi),%eax          # calc Sysmap physaddr
+       movl    %eax,(PROC0PDIR+0*4)(%esi)              # map it in
+       addl    $NBPG, %eax                             # 2nd Sysmap page
+       movl    %eax,(PROC0PDIR+1*4)(%esi)              # map it too
+       /* code below assumes %eax == sysmap physaddr, so we adjust it back */
+       subl    $NBPG, %eax
+
+/*
+ * Map kernel PDEs: this is the real mapping used 
+ * after the temp mapping outlives its usefulness.
  */
-       /* Install a PDE for temporary double map of kernel text. */
-       leal    (SYSMAP+PG_V|PG_KW)(%esi),%eax          # pte for KPT in proc 0,
-       movl    %eax,(PROC0PDIR+0*4)(%esi)              # which is where temp maps!
-       /* Map kernel PDEs. */
-       movl    $NKPDE,%ecx                             # for this many pde s,
-       leal    (PROC0PDIR+KPTDI*4)(%esi),%ebx          # offset of pde for kernel
+       movl    $NKPDE,%ecx                             # count of pde's
+       leal    (PROC0PDIR+KPTDI*4)(%esi),%ebx          # map them high
        fillkpt
 
        /* Install a PDE recursively mapping page directory as a page table! */
        leal    (PROC0PDIR+PG_V|PG_KW)(%esi),%eax       # pte for ptd
-       movl    %eax,(PROC0PDIR+PTDPTDI*4)(%esi)        # which is where PTmap maps!
+       movl    %eax,(PROC0PDIR+PTDPTDI*4)(%esi)        # phys addr from above
 
        /* Save phys. addr of PTD, for libkvm. */
        movl    %esi,RELOC(_PTDpaddr)
@@ -596,6 +605,7 @@ try586:     /* Use the `cpuid' instruction. */
 begin:
        /* Now running relocated at KERNBASE.  Remove double mapping. */
        movl    $0,(PROC0PDIR+0*4)(%esi)
+       movl    $0,(PROC0PDIR+1*4)(%esi)
 
        /* Relocate atdevbase. */
        leal    (TABLESIZE+KERNBASE)(%esi),%edx