lguest re-review

lguest re-review

[Andrew Morton]

Some concern was expressed over the lguest review status, so I shall send
the patches out again for people to review, to test, to make observations
about the author's personal appearance, etc.

I'll plan on sending these patches off to Linus in a week's time, assuming
all goes well.

Thanks.

Re: lguest re-review

[Rusty Russell]

On Wed, 2007-05-09 at 02:51 -0700, Andrew Morton wrote:
> Some concern was expressed over the lguest review status, so I shall send
> the patches out again for people to review, to test, to make observations
> about the author's personal appearance, etc.

Thanks Andrew,

	This means I can finally ack this patch (thanks Eric):

From: ebiederm@xmission.com (Eric W. Biederman)
Subject: [PATCH] Revert "[PATCH] paravirt: Add startup infrastructure for paravirtualization"

This reverts commit c9ccf30d77f04064fe5436027ab9d2230c7cdd94.

Entering the kernel at startup_32 without passing our real mode data
in %esi, and without guaranteeing that physical and virtual addresses
are identity mapped makes head.S impossible to maintain.

The only user of this infrastructure is lguest which is not merged so
nothing we currently support will break by removing this over designed
nightmare, and only the pending lguest patches will be affected. The
pending Xen patches have a different entry point that they use.

We are currently discussing what Xen and lguest need to do to boot the
kernel in a more normal fashion so using startup_32 in this weird
manner is clearly not their long term direction.

So let's remove this code in head.S before it causes brain damage to
people trying to maintain head.S

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>
CC: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 arch/i386/kernel/head.S        |   38 --------------------------------------
 arch/i386/kernel/paravirt.c    |    1 -
 arch/i386/kernel/vmlinux.lds.S |    6 ------
 include/asm-i386/paravirt.h    |    5 -----
 4 files changed, 50 deletions(-)

===================================================================
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -70,12 +70,6 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + 
  */
 .section .text.head,"ax",@progbits
 ENTRY(startup_32)
-
-#ifdef CONFIG_PARAVIRT
-        movl %cs, %eax
-        testl $0x3, %eax
-        jnz startup_paravirt
-#endif
 
 /*
  * Set segments to known values.
@@ -501,38 +495,6 @@ ignore_int:
 	iret
 
 .section .text
-#ifdef CONFIG_PARAVIRT
-startup_paravirt:
-	cld
- 	movl $(init_thread_union+THREAD_SIZE),%esp
-
-	/* We take pains to preserve all the regs. */
-	pushl	%edx
-	pushl	%ecx
-	pushl	%eax
-
-	pushl	$__start_paravirtprobe
-1:
-	movl	0(%esp), %eax
-	cmpl	$__stop_paravirtprobe, %eax
-	je	unhandled_paravirt
-	pushl	(%eax)
-	movl	8(%esp), %eax
-	call	*(%esp)
-	popl	%eax
-
-	movl	4(%esp), %eax
-	movl	8(%esp), %ecx
-	movl	12(%esp), %edx
-
-	addl	$4, (%esp)
-	jmp	1b
-
-unhandled_paravirt:
-	/* Nothing wanted us: we're screwed. */
-	ud2
-#endif
-
 /*
  * Real beginning of normal "text" segment
  */
===================================================================
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -19,7 +19,6 @@
 #include <linux/module.h>
 #include <linux/efi.h>
 #include <linux/bcd.h>
-#include <linux/start_kernel.h>
 #include <linux/highmem.h>
 
 #include <asm/bug.h>
===================================================================
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -80,12 +80,6 @@ SECTIONS
 	EXTRA_RWDATA
 	CONSTRUCTORS
 	} :data
-
-  .paravirtprobe : AT(ADDR(.paravirtprobe) - LOAD_OFFSET) {
-  	__start_paravirtprobe = .;
-	*(.paravirtprobe)
-  	__stop_paravirtprobe = .;
-  }
 
   . = ALIGN(4096);
   .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
===================================================================
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -221,11 +221,6 @@ struct paravirt_ops
 	void (*irq_enable_sysexit)(void);
 	void (*iret)(void);
 };
-
-/* Mark a paravirt probe function. */
-#define paravirt_probe(fn)						\
- static asmlinkage void (*__paravirtprobe_##fn)(void) __attribute_used__ \
-		__attribute__((__section__(".paravirtprobe"))) = fn
 
 extern struct paravirt_ops paravirt_ops;
 

Re: lguest re-review

[Andrew Morton]

On Thu, 10 May 2007 10:24:08 +1000
Rusty Russell <rusty@rustcorp.com.au> wrote:

> On Wed, 2007-05-09 at 02:51 -0700, Andrew Morton wrote:
> > Some concern was expressed over the lguest review status, so I shall send
> > the patches out again for people to review, to test, to make observations
> > about the author's personal appearance, etc.
> 
> Thanks Andrew,
> 
> 	This means I can finally ack this patch (thanks Eric):
> 
> From: ebiederm@xmission.com (Eric W. Biederman)
> Subject: [PATCH] Revert "[PATCH] paravirt: Add startup infrastructure for paravirtualization"
> 
> This reverts commit c9ccf30d77f04064fe5436027ab9d2230c7cdd94.

I don't get it.  Does lguest no longer need this code, or will
it be reintroduced with an lguest merge, or something else?

Re: lguest re-review

[Eric W. Biederman]

Andrew Morton <akpm@linux-foundation.org> writes:

> I don't get it.  Does lguest no longer need this code, or will
> it be reintroduced with an lguest merge, or something else?

No longer needed.

For the short term lguest has a separate entry point.  For the long term
2.6.23 we will rev the boot protocol, so lguest and Xen can work with
a bzImage and use our standard set of kernel parameters.

Eric

Re: lguest re-review

[Rusty Russell]

On Wed, 2007-05-09 at 17:50 -0700, Andrew Morton wrote:
> On Thu, 10 May 2007 10:24:08 +1000
> Rusty Russell <rusty@rustcorp.com.au> wrote:
> 
> > On Wed, 2007-05-09 at 02:51 -0700, Andrew Morton wrote:
> > > Some concern was expressed over the lguest review status, so I shall send
> > > the patches out again for people to review, to test, to make observations
> > > about the author's personal appearance, etc.
> > 
> > Thanks Andrew,
> > 
> > 	This means I can finally ack this patch (thanks Eric):
> > 
> > From: ebiederm@xmission.com (Eric W. Biederman)
> > Subject: [PATCH] Revert "[PATCH] paravirt: Add startup infrastructure for paravirtualization"
> > 
> > This reverts commit c9ccf30d77f04064fe5436027ab9d2230c7cdd94.
> 
> I don't get it.  Does lguest no longer need this code, or will
> it be reintroduced with an lguest merge, or something else?

Lguest no longer needs it (the magic signature patch you took).

HPA and Eric are brewing a new, shinier way for booting not-a-normal-pc
which will address lguest as well as others.  But it seems they first
need to go through the "who knows most about ancient PCs" slapfight.

Thanks!
Rusty.