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 15/25] powerpc/fadump: Update documentation about OPAL platform support
Date: Tue, 16 Jul 2019 17:03:45 +0530 [thread overview]
Message-ID: <156327682571.27462.17734716839038675848.stgit@hbathini.in.ibm.com> (raw)
In-Reply-To: <156327668777.27462.5297279227799429100.stgit@hbathini.in.ibm.com>
With FADump support now available on both pseries and OPAL platforms,
update FADump documentation with these details.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
Documentation/powerpc/firmware-assisted-dump.txt | 104 +++++++++++++---------
1 file changed, 63 insertions(+), 41 deletions(-)
diff --git a/Documentation/powerpc/firmware-assisted-dump.txt b/Documentation/powerpc/firmware-assisted-dump.txt
index 0c6a28c..cd48776 100644
--- a/Documentation/powerpc/firmware-assisted-dump.txt
+++ b/Documentation/powerpc/firmware-assisted-dump.txt
@@ -70,7 +70,8 @@ as follows:
normal.
-- The freshly booted kernel will notice that there is a new
- node (ibm,dump-kernel) in the device tree, indicating that
+ node (ibm,dump-kernel on PSeries or ibm,opal/dump/result-table
+ on OPAL platform) in the device tree, indicating that
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
@@ -93,7 +94,9 @@ as follows:
Please note that the firmware-assisted dump feature
is only available on Power6 and above systems with recent
-firmware versions.
+firmware versions on PSeries (PowerVM) platform and Power9
+and above systems with recent firmware versions on PowerNV
+(OPAL) platform.
Implementation details:
----------------------
@@ -108,57 +111,76 @@ that are run. If there is dump data, then the
/sys/kernel/fadump_release_mem file is created, and the reserved
memory is held.
-If there is no waiting dump data, then only the memory required
-to hold CPU state, HPTE region, boot memory dump and elfcore
-header, is usually reserved at an offset greater than boot memory
-size (see Fig. 1). This area is *not* released: this region will
-be kept permanently reserved, so that it can act as a receptacle
-for a copy of the boot memory content in addition to CPU state
-and HPTE region, in the case a crash does occur. Since this reserved
-memory area is used only after the system crash, there is no point in
-blocking this significant chunk of memory from production kernel.
-Hence, the implementation uses the Linux kernel's Contiguous Memory
-Allocator (CMA) for memory reservation if CMA is configured for kernel.
-With CMA reservation this memory will be available for applications to
-use it, while kernel is prevented from using it. With this FADump will
-still be able to capture all of the kernel memory and most of the user
-space memory except the user pages that were present in CMA region.
+If there is no waiting dump data, then only the memory required to
+hold CPU state, HPTE region, boot memory dump, FADump header and
+elfcore header, is usually reserved at an offset greater than boot
+memory size (see Fig. 1). This area is *not* released: this region
+will be kept permanently reserved, so that it can act as a receptacle
+for a copy of the boot memory content in addition to CPU state and
+HPTE region, in the case a crash does occur.
+
+Since this reserved memory area is used only after the system crash,
+there is no point in blocking this significant chunk of memory from
+production kernel. Hence, the implementation uses the Linux kernel's
+Contiguous Memory Allocator (CMA) for memory reservation if CMA is
+configured for kernel. With CMA reservation this memory will be
+available for applications to use it, while kernel is prevented from
+using it. With this FADump will still be able to capture all of the
+kernel memory and most of the user 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 --->| |
- | | | 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
+ Low memory Top of memory
+ 0 boot memory size |<--- Reserved dump area --->| |
+ | | | Permanent Reservation | |
+ V V | (Preserve area) | V
+ +-----------+-----/ /---+---+----+-------+-----+-----+----+--+
+ | | |///|////| DUMP | HDR | ELF |////| |
+ +-----------+-----/ /---+---+----+-------+-----+-----+----+--+
+ | ^ ^ ^ ^ ^
+ | | | | | |
+ \ CPU HPTE / | |
+ ------------------------------ | |
+ Boot memory content gets transferred | |
+ to reserved area by firmware at the | |
+ time of crash. | |
+ FADump Header |
+ (meta area) |
+ |
+ |
+ Metadata: This area holds a metadata struture whose
+ address is registered with f/w and retrieved in the
+ second kernel after crash, on platforms that support
+ tags (OPAL). Having such structure with info needed
+ to process the crashdump eases dump capture process.
Fig. 1
o Memory Reservation during second kernel after crash
- 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
+ Low memory Top of memory
+ 0 boot memory size |
+ | |<------------ Reserved dump area -------------->|
+ V V |<---- Preserve area ------->| |
+ +-----------+-----/ /---+---+----+-------+-----+-----+----+--+
+ | | |///|////| DUMP | HDR | ELF |////| |
+ +-----------+-----/ /---+---+----+-------+-----+-----+----+--+
+ | |
+ V V
+ Used by second /proc/vmcore
kernel to boot
+
+ +---+
+ |///| -> Regions (CPU, HPTE & Metadata) marked like this in the above
+ +---+ figures are not always present. For example, OPAL platform
+ does not have CPU & HPTE regions while Metadata region is
+ not supported on pSeries currently.
+
Fig. 2
+
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)
next prev parent reply other threads:[~2019-07-16 12:02 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 ` [PATCH v4 03/25] powerpc/fadump: Improve fadump documentation Hari Bathini
2019-08-12 6:55 ` 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 ` Hari Bathini [this message]
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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