From: Hari Bathini <hbathini@linux.ibm.com>
To: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
Vasant Hegde <hegdevasant@linux.ibm.com>,
linuxppc-dev <linuxppc-dev@ozlabs.org>,
Stewart Smith <stewart@linux.ibm.com>
Subject: [PATCH 02/18] powerpc/fadump: Improve fadump documentation
Date: Thu, 21 Feb 2019 23:05:25 +0530 [thread overview]
Message-ID: <155077052570.21014.9544233618306132450.stgit@hbathini.in.ibm.com> (raw)
In-Reply-To: <155077048463.21014.13936958730316555495.stgit@hbathini.in.ibm.com>
The figures depicting FADump's (Firmware-Assisted Dump) memory layout
are missing some finer details like different memory regions and what
they represent. Improve the documentation by updating those details.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
Documentation/powerpc/firmware-assisted-dump.txt | 65 ++++++++++++----------
1 file changed, 35 insertions(+), 30 deletions(-)
diff --git a/Documentation/powerpc/firmware-assisted-dump.txt b/Documentation/powerpc/firmware-assisted-dump.txt
index 18c5fee..059993b 100644
--- a/Documentation/powerpc/firmware-assisted-dump.txt
+++ b/Documentation/powerpc/firmware-assisted-dump.txt
@@ -74,8 +74,9 @@ as follows:
there is crash data available from a previous boot. During
the early boot OS will reserve rest of the memory above
boot memory size effectively booting with restricted memory
- size. This will make sure that the second kernel will not
- touch any of the dump memory area.
+ size. This will make sure that this kernel (also, referred
+ to as second kernel or capture kernel) will not touch any
+ of the dump memory area.
-- User-space tools will read /proc/vmcore to obtain the contents
of memory, which holds the previous crashed kernel dump in ELF
@@ -125,48 +126,52 @@ space memory except the user pages that were present in CMA region.
o Memory Reservation during first kernel
- Low memory Top of memory
- 0 boot memory size |
- | | |<--Reserved dump area -->| |
- V V | Permanent Reservation | V
- +-----------+----------/ /---+---+----+-----------+----+------+
- | | |CPU|HPTE| DUMP |ELF | |
- +-----------+----------/ /---+---+----+-----------+----+------+
- | ^
- | |
- \ /
- -------------------------------------------
- Boot memory content gets transferred to
- reserved area by firmware at the time of
- crash
+ Low memory Top of memory
+ 0 boot memory size |<--Reserved dump area --->| |
+ | | | Permanent Reservation | |
+ V V | (Preserve area) | V
+ +-----------+----------/ /---+---+----+--------+---+----+------+
+ | | |CPU|HPTE| DUMP |HDR|ELF | |
+ +-----------+----------/ /---+---+----+--------+---+----+------+
+ | ^ ^
+ | | |
+ \ / |
+ ----------------------------------- FADump Header
+ Boot memory content gets transferred (meta area)
+ to reserved area by firmware at the
+ time of crash
+
Fig. 1
+
o Memory Reservation during second kernel after crash
- Low memory Top of memory
- 0 boot memory size |
- | |<------------- Reserved dump area ----------- -->|
- V V V
- +-----------+----------/ /---+---+----+-----------+----+------+
- | | |CPU|HPTE| DUMP |ELF | |
- +-----------+----------/ /---+---+----+-----------+----+------+
+ Low memory Top of memory
+ 0 boot memory size |
+ | |<------------- Reserved dump area --------------->|
+ V V |<---- Preserve area ----->| V
+ +-----------+----------/ /---+---+----+--------+---+----+------+
+ | | |CPU|HPTE| DUMP |HDR|ELF | |
+ +-----------+----------/ /---+---+----+--------+---+----+------+
| |
V V
Used by second /proc/vmcore
kernel to boot
Fig. 2
-Currently the dump will be copied from /proc/vmcore to a
-a new file upon user intervention. The dump data available through
-/proc/vmcore will be in ELF format. Hence the existing kdump
-infrastructure (kdump scripts) to save the dump works fine with
-minor modifications.
+Currently the dump will be copied from /proc/vmcore to a new file upon
+user intervention. The dump data available through /proc/vmcore will be
+in ELF format. Hence the existing kdump infrastructure (kdump scripts)
+to save the dump works fine with minor modifications. KDump scripts on
+major Distro releases have already been modified to work seemlessly (no
+user intervention in saving the dump) when FADump is used, instead of
+KDump, as dump mechanism.
The tools to examine the dump will be same as the ones
used for kdump.
How to enable firmware-assisted dump (fadump):
--------------------------------------
+---------------------------------------------
1. Set config option CONFIG_FA_DUMP=y and build kernel.
2. Boot into linux kernel with 'fadump=on' kernel cmdline option.
@@ -189,7 +194,7 @@ NOTE: 1. 'fadump_reserve_mem=' parameter has been deprecated. Instead
old behaviour.
Sysfs/debugfs files:
-------------
+-------------------
Firmware-assisted dump feature uses sysfs file system to hold
the control files and debugfs file to display memory reserved region.
next prev parent reply other threads:[~2019-02-21 17:41 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-21 17:35 [PATCH 00/18] Add FADump support on PowerNV platform Hari Bathini
2019-02-21 17:35 ` [PATCH 01/18] powerpc/fadump: move internal fadump code to a new file Hari Bathini
2019-02-21 17:35 ` Hari Bathini [this message]
2019-02-21 17:35 ` [PATCH 03/18] pseries/fadump: move out platform specific support from generic code Hari Bathini
2019-02-21 17:35 ` [PATCH 04/18] powerpc/fadump: use FADump instead of fadump for how it is pronounced Hari Bathini
2019-02-21 17:35 ` [PATCH 05/18] powerpc/fadump: enable fadump support on OPAL based POWER platform Hari Bathini
2019-02-21 17:35 ` [PATCH 06/18] powerpc/fadump: Update documentation about OPAL platform support Hari Bathini
2019-02-21 17:36 ` [PATCH 07/18] powerpc/fadump: consider reserved ranges while reserving memory Hari Bathini
2019-02-21 17:36 ` [PATCH 08/18] powerpc/fadump: consider reserved ranges while releasing memory Hari Bathini
2019-02-21 17:36 ` [PATCH 09/18] powernv/fadump: process architected register state data provided by firmware Hari Bathini
2019-02-21 17:36 ` [PATCH 10/18] powernv/fadump: add support to preserve crash data on FADUMP disabled kernel Hari Bathini
2019-02-21 17:36 ` [PATCH 11/18] powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP Hari Bathini
2019-02-21 17:36 ` [PATCH 12/18] powerpc/powernv: export /proc/opalcore for analysing opal crashes Hari Bathini
2019-02-21 17:36 ` [PATCH 13/18] powernv/fadump: Skip processing /proc/vmcore when only OPAL core exists Hari Bathini
2019-02-21 17:37 ` [PATCH 14/18] powernv/opalcore: provide an option to invalidate /proc/opalcore file Hari Bathini
2019-02-21 17:37 ` [PATCH 15/18] powernv/fadump: consider f/w load area Hari Bathini
2019-02-21 17:37 ` [PATCH 16/18] powernv/fadump: update documentation about option to release opalcore Hari Bathini
2019-02-21 17:37 ` [PATCH 17/18] powernv/fadump: use backup area to map PIR to logical CPUs Hari Bathini
2019-02-21 17:37 ` [PATCH 18/18] powerpc/fadump: Update documentation about backup area support Hari Bathini
2019-02-27 3:37 ` [PATCH 00/18] Add FADump support on PowerNV platform Daniel Axtens
2019-02-28 5:02 ` Hari Bathini
2019-02-27 4:18 ` Nicholas Piggin
2019-02-28 5:24 ` Hari Bathini
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