lguest: update comments

#include <asm/bootparam.h>

#include "../../../include/linux/lguest_launcher.h"

/*L:110

 * We can ignore the 42 include files we need for this program, but I do want

 * We can ignore the 43 include files we need for this program, but I do want

 * to draw attention to the use of kernel-style types.

 *

 * As Linus said, "C is a Spartan language, and so should your naming be."  I

typedef uint8_t u8;

/*:*/

#define PAGE_PRESENT 0x7 	/* Present, RW, Execute */

#define BRIDGE_PFX "bridge:"

#ifndef SIOCBRADDIF

#define SIOCBRADDIF	0x89a2		/* add interface to bridge      */

 * --sharenet=<name> option which opens or creates a named pipe.  This can be

 * used to send packets to another guest in a 1:1 manner.

 *

 * More sopisticated is to use one of the tools developed for project like UML

 * More sophisticated is to use one of the tools developed for project like UML

 * to do networking.

 *

 * Faster is to do virtio bonding in kernel.  Doing this 1:1 would be

 * multiple inter-guest channels behind one interface, although it would

 * require some manner of hotplugging new virtio channels.

 *

 * Finally, we could implement a virtio network switch in the kernel.

 * Finally, we could use a virtio network switch in the kernel, ie. vhost.

:*/

static u32 str2ip(const char *ipaddr)

	/* Tell the entry path not to try to reload segment registers. */

	boot->hdr.loadflags |= KEEP_SEGMENTS;

	/*

	 * We tell the kernel to initialize the Guest: this returns the open

	 * /dev/lguest file descriptor.

	 */

	/* We tell the kernel to initialize the Guest. */

	tell_kernel(start);

	/* Ensure that we terminate if a device-servicing child dies. */

		     : "memory");

	return call;

}

/*:*/

/* Can't use our min() macro here: needs to be a constant */

#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)

#include <asm/stackprotector.h>

#include <asm/reboot.h>		/* for struct machine_ops */

/*G:010 Welcome to the Guest!

/*G:010

 * Welcome to the Guest!

 *

 * The Guest in our tale is a simple creature: identical to the Host but

 * behaving in simplified but equivalent ways.  In particular, the Guest is the

#endif

/*G:036

 * When lazy mode is turned off reset the per-cpu lazy mode variable and then

 * issue the do-nothing hypercall to flush any stored calls.

:*/

 * When lazy mode is turned off, we issue the do-nothing hypercall to

 * flush any stored calls, and call the generic helper to reset the

 * per-cpu lazy mode variable.

 */

static void lguest_leave_lazy_mmu_mode(void)

{

	hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);

	paravirt_leave_lazy_mmu();

}

/*

 * We also catch the end of context switch; we enter lazy mode for much of

 * that too, so again we need to flush here.

 *

 * (Technically, this is lazy CPU mode, and normally we're in lazy MMU

 * mode, but unlike Xen, lguest doesn't care about the difference).

 */

static void lguest_end_context_switch(struct task_struct *next)

{

	hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);

#include <asm/processor-flags.h>

/*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).

 * Our story starts with the bzImage: booting starts at startup_32 in

 * arch/x86/boot/compressed/head_32.S.  This merely uncompresses the real

 * kernel in place and then jumps into it: startup_32 in

 * arch/x86/kernel/head_32.S.  Both routines expects a boot header in the %esi

 * register, 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.

 * header and kernel command line somewhere safe, and populates some initial

 * page tables.  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

 * addesses (around 0), not above PAGE_OFFSET as most code expects

 * (eg. 0xC0000000).  Jumps are relative, so they're OK, but we can't touch any

 * data without remembering to subtract __PAGE_OFFSET!

 *

	/*

	 * Now the Switcher is mapped at the right address, we can't fail!

	 * Copy in the compiled-in Switcher code (from <arch>_switcher.S).

	 * Copy in the compiled-in Switcher code (from x86/switcher_32.S).

	 */

	memcpy(switcher_vma->addr, start_switcher_text,

	       end_switcher_text - start_switcher_text);