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| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-06-13 17:55:08 +0200 |
|---|---|---|
| committer | Mike Rapoport (IBM) <rppt@kernel.org> | 2024-06-19 17:05:14 +0200 |
| commit | d9d814eebb1ae9742e7fd7f39730653b16326bd4 (patch) | |
| tree | dcb83a31c4cf188d2f225ef870ca2d8c14f8ef41 /Documentation | |
| parent | mm/memblock: Add "reserve_mem" to reserved named memory at boot up (diff) | |
| download | linux-d9d814eebb1ae9742e7fd7f39730653b16326bd4.tar.xz linux-d9d814eebb1ae9742e7fd7f39730653b16326bd4.zip | |
pstore/ramoops: Add ramoops.mem_name= command line option
Add a method to find a region specified by reserve_mem=nn:align:name for
ramoops. Adding a kernel command line parameter:
reserve_mem=12M:4096:oops ramoops.mem_name=oops
Will use the size and location defined by the memmap parameter where it
finds the memory and labels it "oops". The "oops" in the ramoops option
is used to search for it.
This allows for arbitrary RAM to be used for ramoops if it is known that
the memory is not cleared on kernel crashes or soft reboots.
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20240613155527.591647061@goodmis.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/ramoops.rst | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/admin-guide/ramoops.rst b/Documentation/admin-guide/ramoops.rst index e9f85142182d..6f534a707b2a 100644 --- a/Documentation/admin-guide/ramoops.rst +++ b/Documentation/admin-guide/ramoops.rst @@ -23,6 +23,8 @@ and type of the memory area are set using three variables: * ``mem_size`` for the size. The memory size will be rounded down to a power of two. * ``mem_type`` to specify if the memory type (default is pgprot_writecombine). + * ``mem_name`` to specify a memory region defined by ``reserve_mem`` command + line parameter. Typically the default value of ``mem_type=0`` should be used as that sets the pstore mapping to pgprot_writecombine. Setting ``mem_type=1`` attempts to use @@ -118,6 +120,17 @@ Setting the ramoops parameters can be done in several different manners: return ret; } + D. Using a region of memory reserved via ``reserve_mem`` command line + parameter. The address and size will be defined by the ``reserve_mem`` + parameter. Note, that ``reserve_mem`` may not always allocate memory + in the same location, and cannot be relied upon. Testing will need + to be done, and it may not work on every machine, nor every kernel. + Consider this a "best effort" approach. The ``reserve_mem`` option + takes a size, alignment and name as arguments. The name is used + to map the memory to a label that can be retrieved by ramoops. + + reserver_mem=2M:4096:oops ramoops.mem_name=oops + You can specify either RAM memory or peripheral devices' memory. However, when specifying RAM, be sure to reserve the memory by issuing memblock_reserve() very early in the architecture code, e.g.:: |