#include <asm/thread_info.h>
#include <asm/processor-flags.h>
-/*G:020 This is where we begin: head.S notes that the boot header's platform
- * type field is "1" (lguest), so calls us here.
+/*G:020 Our story starts with the kernel booting into startup_32 in
+ * arch/x86/kernel/head_32.S. It expects a boot header, which is created by
+ * the bootloader (the Launcher in our case).
+ *
+ * The startup_32 function does very little: it clears the uninitialized global
+ * C variables which we expect to be zero (ie. BSS) and then copies the boot
+ * header and kernel command line somewhere safe. Finally it checks the
+ * 'hardware_subarch' field. This was introduced in 2.6.24 for lguest and Xen:
+ * if it's set to '1' (lguest's assigned number), then it calls us here.
*
* WARNING: be very careful here! We're running at addresses equal to physical
* addesses (around 0), not above PAGE_OFFSET as most code expectes
* (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any
- * data.
+ * data without remembering to subtract __PAGE_OFFSET!
*
* The .section line puts this code in .init.text so it will be discarded after
* boot. */
movl $lguest_data - __PAGE_OFFSET, %edx
int $LGUEST_TRAP_ENTRY
- /* The Host put the toplevel pagetable in lguest_data.pgdir. The movsl
- * instruction uses %esi implicitly as the source for the copy we'
- * about to do. */
- movl lguest_data - __PAGE_OFFSET + LGUEST_DATA_pgdir, %esi
-
- /* Copy first 32 entries of page directory to __PAGE_OFFSET entries.
- * This means the first 128M of kernel memory will be mapped at
- * PAGE_OFFSET where the kernel expects to run. This will get it far
- * enough through boot to switch to its own pagetables. */
- movl $32, %ecx
- movl %esi, %edi
- addl $((__PAGE_OFFSET >> 22) * 4), %edi
- rep
- movsl
-
/* Set up the initial stack so we can run C code. */
movl $(init_thread_union+THREAD_SIZE),%esp