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

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Message-ID: <CAE9FiQUgqRLO4O4HFBC_D5o8TQhnouEaDNq82wdwuu57=OsoZQ@mail.gmail.com>
Date:	Mon, 14 Jan 2013 20:45:43 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Thomas Renninger <trenn@...e.de>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	MUNEDA Takahiro <muneda.takahiro@...fujitsu.com>,
	Takao Indoh <indou.takao@...fujitsu.com>,
	linux-pci@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, andi@...stfloor.org,
	tokunaga.keiich@...fujitsu.com, kexec@...ts.infradead.org,
	hbabu@...ibm.com, mingo@...hat.com, ddutile@...hat.com,
	vgoyal@...hat.com, ishii.hironobu@...fujitsu.com,
	bhelgaas@...gle.com, tglx@...utronix.de, khalid@...ehiking.org,
	horms@...ge.net.au
Subject: Re: [PATCH] x86 e820: only void usable memory areas in
 memmap=exactmap case

On Mon, Jan 14, 2013 at 4:54 PM, Thomas Renninger <trenn@...e.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@...e.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

Download attachment "e820_resetusablemap.patch" of type "application/octet-stream" (1161 bytes)