Re: Bug#234976: kernel-source-2.6.4: Software Suspend doesn't work

[Pavel Machek]

Hi!

> > --- tmp/linux/arch/i386/power/cpu.c	2003-09-28 22:05:30.000000000 +0200
> > +++ linux/arch/i386/power/cpu.c	2004-04-27 14:44:03.000000000 +0200
> > @@ -35,6 +35,9 @@
> >  unsigned long saved_context_esi, saved_context_edi;
> >  unsigned long saved_context_eflags;
> >  
> > +/* Special page directory for resume */
> > +char swsusp_pg_dir[PAGE_SIZE];
> > +
> 
> You forgot to mark this as nosave.

More importantly, I forgot to mark it as aligned on PAGE_SIZE. Oops
(er... double fault). Here's fixed patch, and this one should work.

Andrew, the crashes with intel-agp were not driver fault after
all. swsusp assumed 4MB pages, and intel-agp driver broke 4MB page
down, resulting in nasty crash.

Herbert's solution was to copy memory backwards, and avoid the crash
by luck (But thanks a lot for explaining me the problem!).

Non-PSE cpus are still not supported; but it should be easier when we
are running in pagedir with identity-mapped pages.

This solution copies page table at boot, where it is "known good",
still 4MB. Could you apply it?

								Pavel

--- tmp/linux/arch/i386/mm/init.c	2004-04-05 10:45:11.000000000 +0200
+++ linux/arch/i386/mm/init.c	2004-04-27 23:39:07.000000000 +0200
@@ -331,6 +331,13 @@
 void zap_low_mappings (void)
 {
 	int i;
+
+#ifdef CONFIG_SOFTWARE_SUSPEND
+	{
+		extern char swsusp_pg_dir[PAGE_SIZE];
+		memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
+	}
+#endif
 	/*
 	 * Zap initial low-memory mappings.
 	 *
--- tmp/linux/arch/i386/power/cpu.c	2003-09-28 22:05:30.000000000 +0200
+++ linux/arch/i386/power/cpu.c	2004-04-27 23:41:01.000000000 +0200
@@ -35,6 +35,10 @@
 unsigned long saved_context_esi, saved_context_edi;
 unsigned long saved_context_eflags;
 
+/* Special page directory for resume */
+char __nosavedata swsusp_pg_dir[PAGE_SIZE]
+                  __attribute__ ((aligned (PAGE_SIZE)));
+
 extern void enable_sep_cpu(void *);
 
 void save_processor_state(void)
--- tmp/linux/arch/i386/power/swsusp.S	2003-09-28 22:05:30.000000000 +0200
+++ linux/arch/i386/power/swsusp.S	2004-04-27 14:41:54.000000000 +0200
@@ -29,7 +38,7 @@
 	jmp .L1449
 	.p2align 4,,7
 .L1450:
-	movl $swapper_pg_dir-__PAGE_OFFSET,%ecx
+	movl $swsusp_pg_dir-__PAGE_OFFSET,%ecx
 	movl %ecx,%cr3
 
 	call do_magic_resume_1
--- tmp/linux/include/asm-i386/suspend.h	2003-09-28 22:06:36.000000000 +0200
+++ linux/include/asm-i386/suspend.h	2004-04-27 23:10:24.000000000 +0200
@@ -9,6 +9,9 @@
 static inline int
 arch_prepare_suspend(void)
 {
+	/* If you want to make non-PSE machine work, turn off paging
+           in do_magic. swsusp_pg_dir should have identity mapping, so
+           it could work...  */
 	if (!cpu_has_pse)
 		return -EPERM;
 	return 0;

-- 
934a471f20d6580d5aad759bf0d97ddc
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