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    SubjectRe: [PATCH 1/2] x86 boot: add E820_RESVD_KERN
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    On Mon, 2008-06-30 at 00:34 -0700, Yinghai Lu wrote:
    > On Mon, Jun 30, 2008 at 12:03 AM, Huang, Ying <ying.huang@intel.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@intel.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@gmail.com> wrote:
    > >> >> > On Thu, Jun 26, 2008 at 12:48 AM, Huang, Ying <ying.huang@intel.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.

    I mean memory area reserved with reserved_early() or e820_update_range()
    before reserve_setup_data() is called.

    And because there is no conflict check in e820_update_range(), what to
    deal with potential conflict between setup_data and other memory area
    regardless which one is reserved earlier?


    Another issue related:

    Because some memmap entries are available via extended E820 memmap
    (SETUP_E820_EXT), it is not strictly safe to use e820_update_range()
    between setup_memory_map() and parse_setup_data(). It may be better to
    parse extended E820 memmap right after setup_memory_map().

    Best Regards,
    Huang Ying
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