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Bug 455423

Summary: x86: insert_resorce for lapic addr after e820_reserve_resources
Product: Red Hat Enterprise Linux 5 Reporter: Prarit Bhargava <prarit>
Component: kernelAssignee: Prarit Bhargava <prarit>
Status: CLOSED NOTABUG QA Contact: Martin Jenner <mjenner>
Severity: low Docs Contact:
Priority: low    
Version: 5.3CC: vgoyal
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-08-07 12:06:40 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 455409    
Description Flags
Upstream fix for this issue none

Description Prarit Bhargava 2008-07-15 14:02:23 UTC
Backport 1e934dda0c77c8ad13fdda02074f2cfcea118a56

    x86: insert_resorce for lapic addr after e820_reserve_resources
    when comparing the e820 direct from BIOS, and the one by kexec:
     BIOS-provided physical RAM map:
    - BIOS-e820: 0000000000000000 - 0000000000097400 (usable)
    + BIOS-e820: 0000000000000100 - 0000000000097400 (usable)
      BIOS-e820: 0000000000097400 - 00000000000a0000 (reserved)
      BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
      BIOS-e820: 0000000000100000 - 00000000dffa0000 (usable)
    - BIOS-e820: 00000000dffae000 - 00000000dffb0000 type 9
    + BIOS-e820: 00000000dffae000 - 00000000dffb0000 (reserved)
      BIOS-e820: 00000000dffb0000 - 00000000dffbe000 (ACPI data)
      BIOS-e820: 00000000dffbe000 - 00000000dfff0000 (ACPI NVS)
      BIOS-e820: 00000000dfff0000 - 00000000e0000000 (reserved)
      BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
    - BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
                 =======> that is the local apic address... somewhere we lost it
      BIOS-e820: 00000000ff700000 - 0000000100000000 (reserved)
      BIOS-e820: 0000000100000000 - 0000004020000000 (usable)
    found one entry about reserved is missing for the kernel by kexec.
    it turns out init_apic_mappings is called before e820_reserve_resources
    in setup_arch. but e820_reserve_resources is using request_resource.
    it will not handle the conflicts.
    there are three ways to fix it:
    1. change request_resource in e820_reserve_resources to to insert_resource
    2. move init_apic_mappings after e820_reserve_resources
    3. use late_initcall to insert lapic resource.
    this patch is using method 3, that is less intrusive.
    in later version could consider to use method 1.
    before patch
    fed20000-ffffffff : PCI Bus #00
      fee00000-fee00fff : Local APIC
      fefff000-feffffff : pnp 00:09
      ff700000-ffffffff : reserved
    with patch will get map in first kernel
    fed20000-ffffffff : PCI Bus #00
      fee00000-fee00fff : Local APIC
        fee00000-fee00fff : reserved
      fefff000-feffffff : pnp 00:09
      ff700000-ffffffff : reserved
    Signed-off-by: Yinghai Lu <>
    Signed-off-by: Ingo Molnar <>

Comment 1 Prarit Bhargava 2008-07-15 14:02:23 UTC
Created attachment 311827 [details]
Upstream fix for this issue

Comment 2 Prarit Bhargava 2008-07-21 14:49:46 UTC
I've tried reproducing this issue on a few systems but have been unable to do so.  

Vivek -- do you think we need this patch?


Comment 3 Vivek Goyal 2008-07-24 13:45:29 UTC

I think we might not require this patch. Instead we might require another patch
which changes
request_resource() to insert_resources() in e820_request_resource() function. I
will have to search for commit id.

Before that I need to talk to Yinghai Lu, about the relevance of his changes. My
feeling is that now his patch is redundant. I will send him a mail now..


Comment 4 Vivek Goyal 2008-07-24 14:00:17 UTC

IIUC, problem was that in second kernel for kexec, reserved area for LAPIC was
not being reported and that must have run into some issues.

It happened because lapic did resource reservation before e820 could do that. We
could solve the problem by using insert_resource() in e820_reserve_resource()
and I think following patch from yinghai is doing that.



Comment 5 Prarit Bhargava 2008-08-07 12:06:40 UTC