Re: [PATCH] x86 e820: only void usable memory areas in memmap=exactmap case

[Yinghai Lu <yinghai@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 1508 bytes --]

On Mon, Jan 14, 2013 at 4:54 PM, Thomas Renninger <trenn@suse.de> wrote:
> On Monday, January 14, 2013 11:04:36 AM Yinghai Lu wrote:
>> On Mon, Jan 14, 2013 at 7:05 AM, Thomas Renninger <trenn@suse.de> wrote:
>> > What is this for?:
>> > @@ -871,6 +879,11 @@ static int __init parse_memmap_one(char
>> >
>> >         userdef = 1;
>> >         if (*p == '@') {
>> >
>> >                 start_at = memparse(p+1, &p);
>> >
>> > +               if (exactusablemap_parsed) {
>> > +                       /* remove all range with other types */
>> > +                       e820_remove_range(start_at, mem_size,
>> > +                                                E820_RAM, 0);
>> > +               }
>> >
>> >                 e820_add_region(start_at, mem_size, E820_RAM);
>> >
>> >         } else if (*p == '#') {
>> >
>> >                 start_at = memparse(p+1, &p);
>>
>> remove all old renges before add E820_RAM, otherwise new add E820
>> ranges could be ignored.
> But this is intended?
> kexec must never request reserved memory to be used as ordinary E820_RAM
> by the kdump kernel.
> This also reverts what exactusablemap is all about:
> Keep all reserved memory ranges of the original BIOS map.
>
> Above would again wrongly remove the mmconf and other reserved regions
> if kexec passes memmap=exactuseablemap,x@y
>
> From what I can see the patch looks fine, but above part should
> simply be left out.

then, I would like to rename it to resetusablemap instead.

like attached.

Thanks

Yinghai

[-- Attachment #2: e820_resetusablemap.patch --]
[-- Type: application/octet-stream, Size: 1161 bytes --]

---
 arch/x86/kernel/e820.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -845,7 +845,7 @@ static int __init parse_memmap_one(char
 	if (!p)
 		return -EINVAL;
 
-	if (!strncmp(p, "exactmap", 8)) {
+	if (!strncmp(p, "exactmap", 8) || !strncmp(p, "resetusablemap", 14)) {
 		if (exactmap_parsed)
 			return 0;
 
@@ -858,7 +858,11 @@ static int __init parse_memmap_one(char
 		 */
 		saved_max_pfn = e820_end_of_ram_pfn();
 #endif
-		e820.nr_map = 0;
+		if (!strncmp(p, "resetusablemap", 14)) {
+			/* remove all old E820_RAM ranges */
+			e820_remove_range(0, ULLONG_MAX, E820_RAM, 1);
+		} else
+			e820.nr_map = 0;
 		userdef = 1;
 		return 0;
 	}
@@ -890,6 +894,11 @@ static int __init parse_memmap_opt(char
 	p = strstr(p, "exactmap");
 	if (p)
 		parse_memmap_one("exactmap");
+	else {
+		p = strstr(boot_command_line, "resetusablemap");
+		if (p)
+			parse_memmap_one("resetusablemap");
+	}
 
 	while (str) {
 		char *k = strchr(str, ',');