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linux_old1/Documentation/devicetree/bindings/reserved-memory/ramoops.txt

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pstore/ram: add Device Tree bindings ramoops is one of the remaining places where ARM vendors still rely on board-specific shims. Device Tree lets us replace those shims with generic code. These bindings mirror the ramoops module parameters, with two small differences: (1) dump_oops becomes an optional "no-dump-oops" property, since ramoops sets dump_oops=1 by default. (2) mem_type=1 becomes the more self-explanatory "unbuffered" property. Signed-off-by: Greg Hackmann <ghackmann@google.com> [fixed platform_get_drvdata() crash, thanks to Brian Norris] [switched from u64 to u32 to simplify code, various whitespace fixes] [use dev_of_node() to gain code-elimination for CONFIG_OF=n] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-01-08 07:40:56 +08:00
Ramoops oops/panic logger
=========================
ramoops provides persistent RAM storage for oops and panics, so they can be
ramoops: use DT reserved-memory bindings Instead of a ramoops-specific node, use a child node of /reserved-memory. This requires that of_platform_device_create() be explicitly called for the node, though, since "/reserved-memory" does not have its own "compatible" property. Suggested-by: Rob Herring <robh@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Rob Herring <robh@kernel.org>
2016-07-30 09:11:32 +08:00
recovered after a reboot. This is a child-node of "/reserved-memory", and
is named "ramoops" after the backend, rather than "pstore" which is the
subsystem.
pstore/ram: add Device Tree bindings ramoops is one of the remaining places where ARM vendors still rely on board-specific shims. Device Tree lets us replace those shims with generic code. These bindings mirror the ramoops module parameters, with two small differences: (1) dump_oops becomes an optional "no-dump-oops" property, since ramoops sets dump_oops=1 by default. (2) mem_type=1 becomes the more self-explanatory "unbuffered" property. Signed-off-by: Greg Hackmann <ghackmann@google.com> [fixed platform_get_drvdata() crash, thanks to Brian Norris] [switched from u64 to u32 to simplify code, various whitespace fixes] [use dev_of_node() to gain code-elimination for CONFIG_OF=n] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-01-08 07:40:56 +08:00
Parts of this storage may be set aside for other persistent log buffers, such
as kernel log messages, or for optional ECC error-correction data. The total
size of these optional buffers must fit in the reserved region.
Any remaining space will be used for a circular buffer of oops and panic
records. These records have a configurable size, with a size of 0 indicating
that they should be disabled.
At least one of "record-size", "console-size", "ftrace-size", or "pmsg-size"
must be set non-zero, but are otherwise optional as listed below.
Required properties:
- compatible: must be "ramoops"
ramoops: use DT reserved-memory bindings Instead of a ramoops-specific node, use a child node of /reserved-memory. This requires that of_platform_device_create() be explicitly called for the node, though, since "/reserved-memory" does not have its own "compatible" property. Suggested-by: Rob Herring <robh@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Rob Herring <robh@kernel.org>
2016-07-30 09:11:32 +08:00
- reg: region of memory that is preserved between reboots
pstore/ram: add Device Tree bindings ramoops is one of the remaining places where ARM vendors still rely on board-specific shims. Device Tree lets us replace those shims with generic code. These bindings mirror the ramoops module parameters, with two small differences: (1) dump_oops becomes an optional "no-dump-oops" property, since ramoops sets dump_oops=1 by default. (2) mem_type=1 becomes the more self-explanatory "unbuffered" property. Signed-off-by: Greg Hackmann <ghackmann@google.com> [fixed platform_get_drvdata() crash, thanks to Brian Norris] [switched from u64 to u32 to simplify code, various whitespace fixes] [use dev_of_node() to gain code-elimination for CONFIG_OF=n] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-01-08 07:40:56 +08:00
Optional properties:
- ecc-size: enables ECC support and specifies ECC buffer size in bytes
(defaults to 0: no ECC)
- record-size: maximum size in bytes of each dump done on oops/panic
(defaults to 0: disabled)
- console-size: size in bytes of log buffer reserved for kernel messages
(defaults to 0: disabled)
- ftrace-size: size in bytes of log buffer reserved for function tracing and
profiling (defaults to 0: disabled)
- pmsg-size: size in bytes of log buffer reserved for userspace messages
(defaults to 0: disabled)
- unbuffered: if present, use unbuffered mappings to map the reserved region
(defaults to buffered mappings)
- no-dump-oops: if present, only dump panics (defaults to panics and oops)
ramoops: Split ftrace buffer space into per-CPU zones If the RAMOOPS_FLAG_FTRACE_PER_CPU flag is passed to ramoops pdata, split the ftrace space into multiple zones depending on the number of CPUs. This speeds up the performance of function tracing by about 280% in my tests as we avoid the locking. The trade off being lesser space available per CPU. Let the ramoops user decide which option they want based on pdata flag. Signed-off-by: Joel Fernandes <joelaf@google.com> [kees: added max_ftrace_cnt to track size, added DT logic and docs] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-10-20 15:34:04 +08:00
- flags: if present, pass ramoops behavioral flags (defaults to 0,
see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).