* How to tell kernel that a region of memory is reserved (in middle of ram)?
@ 2010-06-02 10:11 Maxim Levitsky
2010-06-02 20:31 ` Yinghai Lu
0 siblings, 1 reply; 2+ messages in thread
From: Maxim Levitsky @ 2010-06-02 10:11 UTC (permalink / raw)
To: linux-kernel
Hi,
I need to reserve a region of ram to store there a ramoops buffer.
I need to do so early so kernel doesn't overwrite the existing contents.
How to do it?
I noticed that doing memmap=20M$0x70000000 crashes the system although
it promised to work.
Is that a bug?
I have 2GB system with following memory map:
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
[ 0.000000] BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 000000007fcfd000 (usable)
[ 0.000000] BIOS-e820: 000000007fcfd000 - 000000007fd08000 (reserved)
[ 0.000000] BIOS-e820: 000000007fd08000 - 000000007fd52000 (usable)
[ 0.000000] BIOS-e820: 000000007fd52000 - 000000007fd55000 (reserved)
[ 0.000000] BIOS-e820: 000000007fd55000 - 000000007fdbb000 (usable)
[ 0.000000] BIOS-e820: 000000007fdbb000 - 000000007fdbf000 (reserved)
[ 0.000000] BIOS-e820: 000000007fdbf000 - 000000007fe70000 (usable)
[ 0.000000] BIOS-e820: 000000007fe70000 - 000000007febf000 (ACPI NVS)
[ 0.000000] BIOS-e820: 000000007febf000 - 000000007ff00000 (ACPI data)
[ 0.000000] BIOS-e820: 000000007ff00000 - 0000000080000000 (reserved)
[ 0.000000] BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
[ 0.000000] BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed1c000 - 00000000fed20000 (reserved)
[ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[ 0.000000] BIOS-e820: 00000000fff00000 - 0000000100000000 (reserved)
Best regards,
Maxim Levitsky
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: How to tell kernel that a region of memory is reserved (in middle of ram)?
2010-06-02 10:11 How to tell kernel that a region of memory is reserved (in middle of ram)? Maxim Levitsky
@ 2010-06-02 20:31 ` Yinghai Lu
0 siblings, 0 replies; 2+ messages in thread
From: Yinghai Lu @ 2010-06-02 20:31 UTC (permalink / raw)
To: Maxim Levitsky; +Cc: linux-kernel
On Wed, Jun 2, 2010 at 3:11 AM, Maxim Levitsky <maximlevitsky@gmail.com> wrote:
> Hi,
>
> I need to reserve a region of ram to store there a ramoops buffer.
> I need to do so early so kernel doesn't overwrite the existing contents.
>
> How to do it?
>
> I noticed that doing memmap=20M$0x70000000 crashes the system although
> it promised to work.
> Is that a bug?
>
> I have 2GB system with following memory map:
>
> [ 0.000000] BIOS-provided physical RAM map:
> [ 0.000000] BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> [ 0.000000] BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> [ 0.000000] BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
> [ 0.000000] BIOS-e820: 0000000000100000 - 000000007fcfd000 (usable)
> [ 0.000000] BIOS-e820: 000000007fcfd000 - 000000007fd08000 (reserved)
> [ 0.000000] BIOS-e820: 000000007fd08000 - 000000007fd52000 (usable)
> [ 0.000000] BIOS-e820: 000000007fd52000 - 000000007fd55000 (reserved)
> [ 0.000000] BIOS-e820: 000000007fd55000 - 000000007fdbb000 (usable)
> [ 0.000000] BIOS-e820: 000000007fdbb000 - 000000007fdbf000 (reserved)
> [ 0.000000] BIOS-e820: 000000007fdbf000 - 000000007fe70000 (usable)
> [ 0.000000] BIOS-e820: 000000007fe70000 - 000000007febf000 (ACPI NVS)
> [ 0.000000] BIOS-e820: 000000007febf000 - 000000007ff00000 (ACPI data)
> [ 0.000000] BIOS-e820: 000000007ff00000 - 0000000080000000 (reserved)
> [ 0.000000] BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fed1c000 - 00000000fed20000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
> [ 0.000000] BIOS-e820: 00000000fff00000 - 0000000100000000 (reserved)
>
kernel version?
you could boot with "debug earlyprintk=ttyS0,115200" to get more info.
YH
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-06-02 10:11 How to tell kernel that a region of memory is reserved (in middle of ram)? Maxim Levitsky
2010-06-02 20:31 ` Yinghai Lu
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