linux-kernel - Re: [PATCH 1/2] x86 boot: add E820_RESVD

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Message-ID: <86802c440806300034x5bb9b7a1s168bbeaee17e5124@mail.gmail.com>
Date:	Mon, 30 Jun 2008 00:34:41 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Huang, Ying" <ying.huang@...el.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, andi@...stfloor.org,
	mingo@...hat.com, tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86 boot: add E820_RESVD_KERN

On Mon, Jun 30, 2008 at 12:03 AM, Huang, Ying <ying.huang@...el.com> wrote:
> On Fri, 2008-06-27 at 15:05 -0700, Yinghai Lu wrote:
>> On Thu, Jun 26, 2008 at 7:48 PM, Huang, Ying <ying.huang@...el.com> wrote:
>> > On Thu, 2008-06-26 at 19:22 -0700, Yinghai Lu wrote:
>> >> On Thu, Jun 26, 2008 at 2:47 AM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
>> >> > On Thu, Jun 26, 2008 at 12:48 AM, Huang, Ying <ying.huang@...el.com> wrote:
>> >> >> On Thu, 2008-06-26 at 00:25 -0700, Yinghai Lu wrote:
>> >> >> [...]
>> >> >>> >                if (pfn >= limit_pfn)
>> >> >>> > @@ -977,7 +978,7 @@ u64 __init early_reserve_e820(u64 startt
>> >> >>> >                return 0;
>> >> >>> >
>> >> >>> >        addr = round_down(start + size - sizet, align);
>> >> >>> > -       e820_update_range(addr, sizet, E820_RAM, E820_RESERVED);
>> >> >>> > +       e820_update_range(addr, sizet, E820_RAM, E820_RESVD_KERN);
>> >> >>>
>> >> >>> this line is not needed.
>> >> >>
>> >> >> Why? Memory reserved by early_rserved_e820 should not be saved during
>> >> >> hibernation? shoudl not be saved by kdump?
>> >> >>
>> >
>> > Can you tell me why this line is not needed?
>> >
>> > [...]
>> >> some like the attach patch...
>> >>
>> >> you still can merge parse_setup_data parse_e820_ext
>> >> also entries in parse_e820_ext is not initialized..., __copy_e820_map
>> >> will do nothing.
>> >
>> > OK. Because some E820 entries are available after parse_setup_data(),
>> > it is better to call reserve_setup_data() after calling
>> > parse_setup_data() if update_e820_range() is used instead of
>> > reserve_early().
>>
>> please modify it and test on your platforms then submit to Ingo..
>
> It seems that there is an issue:
>
> - If parse_setup_data() is called before reserve_setup_data(), and there
> is a conflict between memory area used by setup_data and other memory
> area, it is possible that the contents of setup_data is changed. So that
> system may panic before reporting memory area conflict. And it seems
> that memory area conflict is not checked by e820_update_range().

what is "other memory area"? returned from find_e820_area? no one use that yet.

YH