From: Hari Bathini <hbathini@linux.ibm.com>
To: linuxppc-dev <linuxppc-dev@ozlabs.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
Vasant Hegde <hegdevasant@linux.ibm.com>,
Oliver <oohall@gmail.com>, Nicholas Piggin <npiggin@gmail.com>,
Stewart Smith <stewart@linux.ibm.com>,
Daniel Axtens <dja@axtens.net>
Subject: [PATCH v4 03/25] powerpc/fadump: Improve fadump documentation
Date: Tue, 16 Jul 2019 17:02:15 +0530 [thread overview]
Message-ID: <156327673568.27462.12962666023309715458.stgit@hbathini.in.ibm.com> (raw)
In-Reply-To: <156327668777.27462.5297279227799429100.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 0c41d6d..e9b4e3c 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:[~2019-07-16 11:39 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-16 11:31 [PATCH v4 00/25] Add FADump support on PowerNV platform Hari Bathini
2019-07-16 11:32 ` [PATCH v4 01/25] powerpc/fadump: move internal macros/definitions to a new header Hari Bathini
2019-07-16 11:32 ` [PATCH v4 02/25] powerpc/fadump: move internal code to a new file Hari Bathini
2019-07-16 11:32 ` Hari Bathini [this message]
2019-08-12 6:55 ` [PATCH v4 03/25] powerpc/fadump: Improve fadump documentation Mahesh Jagannath Salgaonkar
2019-07-16 11:32 ` [PATCH v4 04/25] pseries/fadump: move rtas specific definitions to platform code Hari Bathini
2019-07-16 11:32 ` [PATCH v4 05/25] pseries/fadump: introduce callbacks for platform specific operations Hari Bathini
2019-08-12 9:42 ` Mahesh J Salgaonkar
2019-08-14 6:39 ` Hari Bathini
2019-07-16 11:32 ` [PATCH v4 06/25] pseries/fadump: define register/un-register callback functions Hari Bathini
2019-08-12 16:01 ` Mahesh J Salgaonkar
2019-08-14 6:41 ` Hari Bathini
2019-07-16 11:32 ` [PATCH v4 07/25] pseries/fadump: move out platform specific support from generic code Hari Bathini
2019-08-13 5:16 ` Mahesh J Salgaonkar
2019-07-16 11:32 ` [PATCH v4 08/25] powerpc/fadump: use FADump instead of fadump for how it is pronounced Hari Bathini
2019-07-16 11:33 ` [PATCH v4 09/25] opal: add MPIPL interface definitions Hari Bathini
2019-07-16 11:33 ` [PATCH v4 10/25] powernv/fadump: add fadump support on powernv Hari Bathini
2019-07-16 11:33 ` [PATCH v4 11/25] powernv/fadump: register kernel metadata address with opal Hari Bathini
2019-08-13 10:41 ` Mahesh J Salgaonkar
2019-08-14 7:06 ` Hari Bathini
2019-08-14 10:21 ` Mahesh Jagannath Salgaonkar
2019-08-19 15:49 ` Hari Bathini
2019-07-16 11:33 ` [PATCH v4 12/25] powernv/fadump: define register/un-register callback functions Hari Bathini
2019-08-13 14:34 ` Mahesh J Salgaonkar
2019-08-14 7:11 ` Hari Bathini
2019-07-16 11:33 ` [PATCH v4 13/25] powernv/fadump: support copying multiple kernel memory regions Hari Bathini
2019-08-13 15:03 ` Mahesh J Salgaonkar
2019-08-14 7:14 ` Hari Bathini
2019-07-16 11:33 ` [PATCH v4 14/25] powernv/fadump: process the crashdump by exporting it as /proc/vmcore Hari Bathini
2019-08-14 10:18 ` Mahesh J Salgaonkar
2019-08-14 11:11 ` Hari Bathini
2019-07-16 11:33 ` [PATCH v4 15/25] powerpc/fadump: Update documentation about OPAL platform support Hari Bathini
2019-07-16 11:33 ` [PATCH v4 16/25] powerpc/fadump: consider reserved ranges while reserving memory Hari Bathini
2019-07-16 11:34 ` [PATCH v4 17/25] powerpc/fadump: consider reserved ranges while releasing memory Hari Bathini
2019-07-16 11:34 ` [PATCH v4 18/25] powernv/fadump: process architected register state data provided by firmware Hari Bathini
2019-08-14 17:15 ` Mahesh J Salgaonkar
2019-08-16 2:38 ` Hari Bathini
2019-07-16 11:34 ` [PATCH v4 19/25] powernv/fadump: add support to preserve crash data on FADUMP disabled kernel Hari Bathini
2019-08-16 5:01 ` Mahesh J Salgaonkar
2019-07-16 11:34 ` [PATCH v4 20/25] powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP Hari Bathini
2019-07-16 11:34 ` [PATCH v4 21/25] powernv/opalcore: export /sys/firmware/opal/core for analysing opal crashes Hari Bathini
2019-07-16 11:34 ` [PATCH v4 22/25] powernv/fadump: Warn before processing partial crashdump Hari Bathini
2019-08-16 5:59 ` Mahesh J Salgaonkar
2019-07-16 11:34 ` [PATCH v4 23/25] powernv/opalcore: provide an option to invalidate /sys/firmware/opal/core file Hari Bathini
2019-07-16 11:34 ` [PATCH v4 24/25] powernv/fadump: consider f/w load area Hari Bathini
2019-07-16 11:35 ` [PATCH v4 25/25] powernv/fadump: update documentation about option to release opalcore Hari Bathini
2019-07-19 6:19 ` [PATCH v4 00/25] Add FADump support on PowerNV platform Hari Bathini
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