Hi,
below you'll find hopefully the final solution of problem with
"Load-to-TT-RAM" flag on AfterBurner040 and Centurbo2 FastRAM cards.
It's actually generic and should take care of any FastRAM&MMU problem.
--- /tmp/m68kboot/common/atari/linuxboot.c 2004-08-14 09:37:23.000000000
+0200
+++ common/atari/linuxboot.c 2004-08-14 10:23:15.000000000 +0200
@@ -132,6 +132,35 @@
} while(0)
+/* taken from arch/m68k/kernel/sys_m68k.c */
+#define MMU_R_040 0x0001
+#define PAGE_SHIFT (12)
+#define PAGE_SIZE (1UL << PAGE_SHIFT)
+#define PAGE_MASK (~(PAGE_SIZE-1))
+/* Convert virtual (user) address VADDR to physical address PADDR */
+#define virt_to_phys_040(vaddr)
\
+({ \
+ unsigned long _mmusr, _paddr;
\
+ \
+ __asm__ __volatile__ (".chip 68040\n\t" \
+ "ptestr (%1)\n\t" \
+ "movec %%mmusr,%0\n\t" \
+ ".chip 68k" \
+ : "=r" (_mmusr) \
+ : "a" (vaddr)); \
+ _paddr = (_mmusr & MMU_R_040) ? (_mmusr & PAGE_MASK) : 0; \
+ _paddr; \
+})
+
+/* return offset between physical and virtual (MMU remapped) address */
+long phys_offset(u_long vaddr) {
+ if (bi.mch_type == ATARI_MACH_AB40 && ((unsigned long)vaddr & 0xff000000))
+ return virt_to_phys_040(vaddr & PAGE_MASK) - (vaddr & PAGE_MASK);
+ if (getcookie("_CT2", NULL) != -1 && ((unsigned long)vaddr & 0xff000000))
+ return CT2_FAST_START - TT_RAM_BASE;
+ return 0;
+}
+
void linux_boot( void )
{
char *kname;
@@ -141,6 +170,9 @@
u_long kernel_size; /* size of kernel image */
char *memptr; /* addr and size of load region */
u_long memreq;
+ long memptr_mmu_offset; /* physical memptr addr offset */
+ long kernel_mmu_offset; /* physical kernel dest addr offset */
+ long ramdisk_mmu_offset; /* physical ramdisk dest addr offset */
u_long rd_size; /* size of ramdisk and array of pointers to
* its data */
@@ -239,14 +271,6 @@
if (!(memptr = malloc( memreq )))
ERROR( "Unable to allocate %ld kB of memory for kernel%s\n",
memreq / 1024, (rd_size > 0) ? " and ramdisk" : "" );
- /* Second part of the AB40 no-FastRAM test */
- if (bi.mch_type == ATARI_MACH_AB40 && ((unsigned long)memptr & 0xff000000))
- ERROR( "Error: Bootstrap may not allocate memory from FastRAM "
- "on Afterburner040\n" );
- if (getcookie("_CT2", NULL) != -1 &&
- ((unsigned long)memptr & 0xff000000))
- ERROR( "Error: Bootstrap may not allocate memory from TT-RAM "
- "on Centurbo2\n" );
/* clearing the kernel's memory perhaps avoids "uninitialized bss"
* types of bugs... */
@@ -282,6 +306,11 @@
/* copy the boot_info struct to the end of the kernel image */
memcpy( memptr + kernel_size, bi_ptr, bi_size );
+ /* find out the physical offsets if the memory is MMU mapped */
+ memptr_mmu_offset = phys_offset((u_long)memptr);
+ kernel_mmu_offset = phys_offset(start_mem);
+ ramdisk_mmu_offset = phys_offset(bi.ramdisk.addr);
+
/* for those who want to debug */
if (debugflag) {
if (rd_size) {
@@ -294,6 +323,13 @@
printf ("boot_info is at %#lx\n",
start_mem + kernel_size);
+ if (memptr_mmu_offset)
+ printf ("kernel src offset = %#lx\n", memptr_mmu_offset);
+ if (kernel_mmu_offset)
+ printf ("kernel dest offset = %#lx\n", kernel_mmu_offset);
+ if (ramdisk_mmu_offset)
+ printf ("ramdisk dest offset = %#lx\n", ramdisk_mmu_offset);
+
printf ("\nType a key to continue the Linux boot...");
fflush (stdout);
getchar();
@@ -312,6 +348,11 @@
/* ..and any MMU translation */
disable_mmu();
+ /* correct pointers to physical memory after MMU translation was disabled
*/
+ memptr += memptr_mmu_offset;
+ start_mem += kernel_mmu_offset;
+ bi.ramdisk.addr += ramdisk_mmu_offset;
+
/* ++guenther: allow reset if launched with MiNT */
*(long*)0x426 = 0;
