On 2/26/20 10:42 AM, Frédéric Danis wrote:

This patch adds a new pstore command allowing to display or save ramoops logs (oops, panic, console, ftrace and user) generated by a previous kernel crash. PStore parameters can be set in U-Boot configuration file, or at run-time using "pstore set" command. Records size should be the same as the ones used by kernel, and should be a power of 2. This command allows:

• to display uncompressed logs
• to save compressed or uncompressed logs, compressed logs are saved as a compressed stream, it may need some work to be able to decompress it, e.g. adding a fake header: "printf "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x00" | cat - dmesg-ramoops-0.enc.z | gzip -dc"
• ECC part is not used to check memory corruption
• only 1st FTrace log is displayed or saved

Signed-off-by: Frédéric Danis frederic.danis@collabora.com

cmd/Kconfig | 63 ++++++ cmd/Makefile | 1 + cmd/pstore.c | 505 +++++++++++++++++++++++++++++++++++++++++++++++++ doc/index.rst | 7 + doc/pstore.rst | 68 +++++++ 5 files changed, 644 insertions(+) create mode 100644 cmd/pstore.c create mode 100644 doc/pstore.rst

diff --git a/cmd/Kconfig b/cmd/Kconfig index 6403bc45a5..7e78343c3d 100644 --- a/cmd/Kconfig +++ b/cmd/Kconfig @@ -1736,6 +1736,69 @@ config CMD_QFW feature is to allow easy loading of files passed to qemu-system via -kernel / -initrd

+config CMD_PSTORE

• bool "pstore"
• help

•  This provides access to Linux PStore. The main feature is to allow to
  

•  display or save PStore records.
  

Linux PStore can have many backends. I would suggest to mention 'rampoops' explicitely and point to the documentation that you have added.

Please, use 'if CMD_PSTORE' to indent all options depending on CMD_PSTORE'.

+config CMD_PSTORE_ADDR

• hex "Mem Address"

Please, use whole words.

hex "Memory address"

• depends on CMD_PSTORE
• default "0x0"
• help

•  Base addr used for PStore ramoops memory, should be identical to
  

•  ramoops.mem_address parameter used by kernel
  

+config CMD_PSTORE_SIZE

Linux calls the parameter mem_size. So shouldn't we call our parameter CMD_PSTORE_MEM_SIZE.

• hex "Mem size"

hex "Memory size"

• depends on CMD_PSTORE
• default "0x0"

A value of zero will lead to an error in Linux "The memory size and the record/console size must be non-zero".

Please, provide a reasonable default.

• help

•  Size of PStore ramoops memory, should be identical to ramoops.mem_size
  

•  parameter used by kernel
  

Please, describe the constraints on ramoops.mem_size. Does it have to be larger than the some of the following parameters?

+config CMD_PSTORE_RECORD_SIZE

• hex "Dump record size"
• depends on CMD_PSTORE
• default "0x1000"
• help

•  Size of each dump done on oops/panic, should be identical to
  

•  ramoops.record_size parameter used by kernel
  

+config CMD_PSTORE_CONSOLE_SIZE

• hex "Kernel console log size"
• depends on CMD_PSTORE
• default "0x1000"
• help

•  Size of kernel console log, should be identical to
  

•  ramoops.console_size parameter used by kernel
  

Please, mention that this value must be non-zero.

+config CMD_PSTORE_FTRACE_SIZE

• hex "FTrace log size"
• depends on CMD_PSTORE
• default "0x1000"
• help

•  Size of ftrace log, should be identical to ramoops.ftrace_size
  

•  parameter used by kernel
  

+config CMD_PSTORE_PMSG_SIZE

• hex "User space message log size"
• depends on CMD_PSTORE
• default "0x1000"
• help

•  Size of user space message log, should be identical to
  

•  ramoops.pmsg_size parameter used by kernel
  

+config CMD_PSTORE_ECC_SIZE

• int "ECC size"

• depends on CMD_PSTORE

• default "0"

• help

• if non-zero, the option enables ECC support and specifies ECC buffer

• size in bytes (1 is a special value, means 16 bytes ECC), should be

• identical to ramoops.ramoops_ecc parameter used by kernel

• source "cmd/mvebu/Kconfig"

  config CMD_TERMINAL

diff --git a/cmd/Makefile b/cmd/Makefile index f1dd513a4b..06d7ad7375 100644 --- a/cmd/Makefile +++ b/cmd/Makefile @@ -110,6 +110,7 @@ obj-$(CONFIG_CMD_PCI) += pci.o endif obj-$(CONFIG_CMD_PINMUX) += pinmux.o obj-$(CONFIG_CMD_PMC) += pmc.o +obj-$(CONFIG_CMD_PSTORE) += pstore.o obj-$(CONFIG_CMD_PXE) += pxe.o pxe_utils.o obj-$(CONFIG_CMD_WOL) += wol.o obj-$(CONFIG_CMD_QFW) += qfw.o diff --git a/cmd/pstore.c b/cmd/pstore.c new file mode 100644 index 0000000000..a14b8522ce --- /dev/null +++ b/cmd/pstore.c @@ -0,0 +1,505 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright © 2019 Collabora Ltd
• */

+#include <config.h> +#include <common.h> +#include <fs.h> +#include <mapmem.h> +#include <memalign.h> +#include <part.h>

+struct persistent_ram_buffer {

• u32 sig;
• u32 start;
• u32 size;
• u8 data[0];

+};

+#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */ +#define RAMOOPS_KERNMSG_HDR "===="

+#define PSTORE_TYPE_DMESG 0 +#define PSTORE_TYPE_CONSOLE 2 +#define PSTORE_TYPE_FTRACE 3 +#define PSTORE_TYPE_PMSG 7 +#define PSTORE_TYPE_ALL 255

+static phys_addr_t pstore_addr = CONFIG_CMD_PSTORE_ADDR; +static phys_size_t pstore_length = CONFIG_CMD_PSTORE_SIZE; +static unsigned int pstore_record_size = CONFIG_CMD_PSTORE_RECORD_SIZE; +static unsigned int pstore_console_size = CONFIG_CMD_PSTORE_CONSOLE_SIZE; +static unsigned int pstore_ftrace_size = CONFIG_CMD_PSTORE_FTRACE_SIZE; +static unsigned int pstore_pmsg_size = CONFIG_CMD_PSTORE_PMSG_SIZE; +static unsigned int pstore_ecc_size = CONFIG_CMD_PSTORE_ECC_SIZE; +static unsigned int buffer_size;

• /**
• • pstore_read_kmsg_hdr() - Check kernel header and get compression flag if

• •                      available.
    

• • @buffer: Kernel messages buffer.
• • @compressed: Returns TRUE if kernel buffer is compressed, else FALSE.
• • Check if buffer starts with a kernel header of the form:
• • ====<secs>.<nsecs>[-<compression>]\n
• • If <compression> is equal to 'C' then the buffer is compressed, else iter
• • should be 'D'.
• • Return: Length of kernel header.
• */

+static int pstore_read_kmsg_hdr(char *buffer, bool *compressed) +{

• char *ptr = buffer;
• *compressed = false;
• if (strncmp(RAMOOPS_KERNMSG_HDR, ptr, strlen(RAMOOPS_KERNMSG_HDR)) != 0)

• return 0;
  

• ptr += strlen(RAMOOPS_KERNMSG_HDR);
• ptr = strchr(ptr, '\n');
• if (!ptr)

• return 0;
  

• if (ptr[-2] == '-' && ptr[-1] == 'C')

• *compressed = true;
  

• return ptr - buffer + 1;

+}

+/**

• • pstore_get_buffer() - Get unwrapped record buffer
• • @sig: Signature to check
• • @buffer: Buffer containing wrapped record
• • @size: wrapped record size
• • @dest: Buffer used to store unwrapped record
• • The record starts with <signature><start><size> header.
• • The signature is 'DBGC' for all records except for Ftrace's record(s) wich
• • use LINUX_VERSION_CODE ^ 'DBGC'.
• • Use 0 for @sig to prevent checking signature.
• • Start and size are 4 bytes long.
• • Return: record's length
• */

+static u32 pstore_get_buffer(u32 sig, phys_addr_t buffer, u32 size, char *dest) +{

• struct persistent_ram_buffer *prb =

• (struct persistent_ram_buffer *)map_sysmem(buffer, size);
  

• u32 dest_size;
• if (sig == 0 || prb->sig == sig) {

• if (prb->size == 0) {
  

• 	debug("found existing empty buffer\n");
  

Please, use log() as described in doc/README.log. This allows the user to control verbosity if CONFIG_LOG=y.

• 	return 0;
  

• }
  

• if (prb->size > size) {
  

• 	debug("found existing invalid buffer, size %u, start %u\n",
  

• 	      prb->size, prb->start);
  

• 	return 0;
  

• }
  

• } else {

• debug("no valid data in buffer (sig = 0x%08x)\n", prb->sig);
  

• return 0;
  

• }
• debug("found existing buffer, size %u, start %u\n",

•      prb->size, prb->start);
  

• memcpy(dest, &prb->data[prb->start], prb->size - prb->start);
• memcpy(dest + prb->size - prb->start, &prb->data[0], prb->start);
• dest_size = prb->size;
• unmap_sysmem(prb);
• return dest_size;

+}

+/**

• • pstore_init_buffer_size() - Init buffer size to largest record size
• • Records, console, FTrace and user logs can use different buffer sizes.
• • This function allows to retrieve the biggest one.
• */

+static void pstore_init_buffer_size(void) +{

• if (pstore_record_size > buffer_size)

• buffer_size = pstore_record_size;
  

• if (pstore_console_size > buffer_size)

• buffer_size = pstore_console_size;
  

• if (pstore_ftrace_size > buffer_size)

• buffer_size = pstore_ftrace_size;
  

• if (pstore_pmsg_size > buffer_size)

• buffer_size = pstore_pmsg_size;
  

+}

+/**

• • pstore_set() - Initialize PStore settings from command line arguments
• • @cmdtp: Command data struct pointer
• • @flag: Command flag
• • @argc: Command-line argument count
• • @argv: Array of command-line arguments
• • Set pstore reserved memory info, starting at 'addr' for 'len' bytes.
• • Default length for records is 4K.
• • Mandatory arguments:
• • • addr: ramoops starting address
• • • len: ramoops total length
• • Optional arguments:
• • • record-size: size of one panic or oops record ('dump' type)
• • • console-size: size of the kernel logs record
• • • ftrace-size: size of the ftrace record(s), this can be a single record or

• •            divided in parts based on number of CPUs
    

• • • pmsg-size: size of the user space logs record
• • • ecc-size: enables/disables ECC support and specifies ECC buffer size in

• •         bytes (0 disables it, 1 is a special value, means 16 bytes ECC)
    

• • Return: zero on success, CMD_RET_USAGE in case of misuse and negative
• • on error.
• */

+static int pstore_set(cmd_tbl_t *cmdtp, int flag, int argc,

•       char * const argv[])
  

+{

• if (argc < 3)

• return CMD_RET_USAGE;
  

• /* Address is specified since argc > 2

• */
  

• pstore_addr = simple_strtoul(argv[1], NULL, 16);
• /* Length is specified since argc > 2

• */
  

• pstore_length = simple_strtoul(argv[2], NULL, 16);
• if (argc > 3)

• pstore_record_size = simple_strtoul(argv[3], NULL, 16);
  

• if (argc > 4)

• pstore_console_size = simple_strtoul(argv[4], NULL, 16);
  

• if (argc > 5)

• pstore_ftrace_size = simple_strtoul(argv[5], NULL, 16);
  

• if (argc > 6)

• pstore_pmsg_size = simple_strtoul(argv[6], NULL, 16);
  

• if (argc > 7)

• pstore_ecc_size = simple_strtoul(argv[7], NULL, 16);
  

• if (pstore_length < (pstore_record_size + pstore_console_size

• 	     + pstore_ftrace_size + pstore_pmsg_size)) {
  

• printf("pstore <len> should be larger than the sum of all records sizes\n");
  

• pstore_length = 0;
  

• }
• debug("pstore set done: start 0x%08llx - length 0x%llx\n",

•      (unsigned long long)pstore_addr,
  

•      (unsigned long long)pstore_length);
  

• return 0;

+}

+/**

• • pstore_print_buffer() - Print buffer
• • @type: buffer type
• • @buffer: buffer to print
• • @size: buffer size
• • Print buffer type and content
• */

+static void pstore_print_buffer(char *type, char *buffer, u32 size) +{

• u32 i = 0;
• printf("**** %s\n", type);
• while (i < size && buffer[i] != 0) {

• putc(buffer[i]);
  

• i++;
  

• }

+}

+/**

• • pstore_display() - Display existing records in pstore reserved memory
• • @cmdtp: Command data struct pointer
• • @flag: Command flag
• • @argc: Command-line argument count
• • @argv: Array of command-line arguments
• • A 'record-type' can be given to only display records of this kind.
• • If no 'record-type' is given, all valid records are dispayed.
• • 'record-type' can be one of 'dump', 'console', 'ftrace' or 'user'. For 'dump'
• • and 'ftrace' types, a 'nb' can be given to only display one record.
• • Return: zero on success, CMD_RET_USAGE in case of misuse and negative
• • on error.
• */

+static int pstore_display(cmd_tbl_t *cmdtp, int flag, int argc,

• 	  char * const argv[])
  

+{

• int type = PSTORE_TYPE_ALL;
• phys_addr_t ptr;
• char *buffer;
• u32 size;
• int header_len = 0;
• bool compressed;
• if (argc > 1) {

• if (!strcmp(argv[1], "dump"))
  

• 	type = PSTORE_TYPE_DMESG;
  

• else if (!strcmp(argv[1], "console"))
  

• 	type = PSTORE_TYPE_CONSOLE;
  

• else if (!strcmp(argv[1], "ftrace"))
  

• 	type = PSTORE_TYPE_FTRACE;
  

• else if (!strcmp(argv[1], "user"))
  

• 	type = PSTORE_TYPE_PMSG;
  

• else
  

• 	return CMD_RET_USAGE;
  

• }
• if (pstore_length == 0) {

• printf("Please set PStore configuration\n");
  

• return CMD_RET_USAGE;
  

• }
• if (buffer_size == 0)

• pstore_init_buffer_size();
  

• buffer = malloc_cache_aligned(buffer_size);
• if (type == PSTORE_TYPE_DMESG || type == PSTORE_TYPE_ALL) {

• ptr = pstore_addr;
  

• phys_addr_t ptr_end = ptr + pstore_length - pstore_pmsg_size
  

• 		- pstore_ftrace_size - pstore_console_size;
  

• if (argc > 2) {
  

• 	ptr += simple_strtoul(argv[2], NULL, 10)
  

• 		* pstore_record_size;
  

• 	ptr_end = ptr + pstore_record_size;
  

• }
  

• while (ptr < ptr_end) {
  

• 	size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr,
  

• 				 pstore_record_size, buffer);
  

• 	ptr += pstore_record_size;
  

• 	if (size == 0)
  

• 		continue;
  

• 	header_len = pstore_read_kmsg_hdr(buffer, &compressed);
  

• 	if (header_len == 0) {
  

• 		debug("no valid kernel header\n");
  

• 		continue;
  

• 	}
  

• 	if (compressed) {
  

• 		printf("Compressed buffer, display not available\n");
  

• 		continue;
  

• 	}
  

• 	pstore_print_buffer("Dump", buffer + header_len,
  

• 			    size - header_len);
  

• }
  

• }
• if (type == PSTORE_TYPE_CONSOLE || type == PSTORE_TYPE_ALL) {

• ptr = pstore_addr + pstore_length - pstore_pmsg_size
  

• 	- pstore_ftrace_size - pstore_console_size;
  

• size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr,
  

• 			 pstore_console_size, buffer);
  

• if (size != 0)
  

• 	pstore_print_buffer("Console", buffer, size);
  

• }
• if (type == PSTORE_TYPE_FTRACE || type == PSTORE_TYPE_ALL) {

• ptr = pstore_addr + pstore_length - pstore_pmsg_size
  

• - pstore_ftrace_size;
  

• /* The FTrace record(s) uses LINUX_VERSION_CODE ^ 'DBGC'
  

•  * signature, pass 0 to pstore_get_buffer to prevent
  

•  * checking it
  

•  */
  

• size = pstore_get_buffer(0, ptr, pstore_ftrace_size, buffer);
  

• if (size != 0)
  

• 	pstore_print_buffer("FTrace", buffer, size);
  

• }
• if (type == PSTORE_TYPE_PMSG || type == PSTORE_TYPE_ALL) {

• ptr = pstore_addr + pstore_length - pstore_pmsg_size;
  

• size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr,
  

• 			 pstore_pmsg_size, buffer);
  

• if (size != 0)
  

• 	pstore_print_buffer("User", buffer, size);
  

• }
• free(buffer);
• return 0;

+}

+/**

• • pstore_save() - Save existing records from pstore reserved memory
• • @cmdtp: Command data struct pointer
• • @flag: Command flag
• • @argc: Command-line argument count
• • @argv: Array of command-line arguments
• • the records are saved under 'directory path', which should already exist,
• • to partition 'part' on device type 'interface' instance 'dev'
• • Filenames are automatically generated, depending on record type, like in
• • /sys/fs/pstore under Linux
• • Return: zero on success, CMD_RET_USAGE in case of misuse and negative
• • on error.
• */

+static int pstore_save(cmd_tbl_t *cmdtp, int flag, int argc,

•        char * const argv[])
  

+{

• phys_addr_t ptr, ptr_end;
• char *buffer;
• char *save_argv[6];
• char addr[19], length[19];
• char path[256];
• u32 size;
• unsigned int index;
• int header_len = 0;
• bool compressed;
• if (argc < 4)

• return CMD_RET_USAGE;
  

• if (pstore_length == 0) {

• printf("Please set PStore configuration\n");
  

• return CMD_RET_USAGE;
  

• }
• if (buffer_size == 0)

• pstore_init_buffer_size();
  

• buffer = malloc_cache_aligned(buffer_size);
• sprintf(addr, "0x%p", buffer);
• save_argv[0] = argv[0];
• save_argv[1] = argv[1];
• save_argv[2] = argv[2];
• save_argv[3] = addr;
• save_argv[4] = path;
• save_argv[5] = length;
• /* Save all Dump records */
• ptr = pstore_addr;
• ptr_end = ptr + pstore_length - pstore_pmsg_size - pstore_ftrace_size

• 		- pstore_console_size;
  

• index = 0;
• while (ptr < ptr_end) {

• size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr,
  

• 			 pstore_record_size, buffer);
  

• ptr += pstore_record_size;
  

• if (size == 0)
  

• 	continue;
  

• header_len = pstore_read_kmsg_hdr(buffer, &compressed);
  

• if (header_len == 0) {
  

• 	debug("no valid kernel header\n");
  

• 	continue;
  

• }
  

• sprintf(addr, "0x%08lx", (ulong)map_to_sysmem(buffer + header_len));
  

• sprintf(length, "0x%X", size - header_len);
  

• sprintf(path, "%s/dmesg-ramoops-%u%s", argv[3], index,
  

• 	compressed ? ".enc.z" : "");
  

• do_save(cmdtp, flag, 6, save_argv, FS_TYPE_ANY);
  

• index++;
  

• }
• sprintf(addr, "0x%08lx", (ulong)map_to_sysmem(buffer));
• /* Save Console record */
• size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr, pstore_console_size,

• 		 buffer);
  

• if (size != 0) {

• sprintf(length, "0x%X", size);
  

• sprintf(path, "%s/console-ramoops-0", argv[3]);
  

• do_save(cmdtp, flag, 6, save_argv, FS_TYPE_ANY);
  

• }
• ptr += pstore_console_size;
• /* Save FTrace record(s)

• * The FTrace record(s) uses LINUX_VERSION_CODE ^ 'DBGC' signature,
  

• * pass 0 to pstore_get_buffer to prevent checking it
  

• */
  

• size = pstore_get_buffer(0, ptr, pstore_ftrace_size, buffer);
• if (size != 0) {

• sprintf(length, "0x%X", size);
  

• sprintf(path, "%s/ftrace-ramoops-0", argv[3]);
  

• do_save(cmdtp, flag, 6, save_argv, FS_TYPE_ANY);
  

• }
• ptr += pstore_ftrace_size;
• /* Save Console record */
• size = pstore_get_buffer(PERSISTENT_RAM_SIG, ptr, pstore_pmsg_size,

• 		 buffer);
  

• if (size != 0) {

• sprintf(length, "0x%X", size);
  

• sprintf(path, "%s/pmsg-ramoops-0", argv[3]);
  

• do_save(cmdtp, flag, 6, save_argv, FS_TYPE_ANY);
  

• }
• free(buffer);
• return 0;

+}

+static cmd_tbl_t cmd_pstore_sub[] = {

• U_BOOT_CMD_MKENT(set, 8, 0, pstore_set, "", ""),
• U_BOOT_CMD_MKENT(display, 3, 0, pstore_display, "", ""),
• U_BOOT_CMD_MKENT(save, 4, 0, pstore_save, "", ""),

+};

+static int do_pstore(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) +{

• cmd_tbl_t *c;
• if (argc < 2)

• return CMD_RET_USAGE;
  

• /* Strip off leading argument */
• argc--;
• argv++;
• c = find_cmd_tbl(argv[0], cmd_pstore_sub, ARRAY_SIZE(cmd_pstore_sub));
• if (!c)

• return CMD_RET_USAGE;
  

• return c->cmd(cmdtp, flag, argc, argv);

+}

+U_BOOT_CMD(pstore, 10, 0, do_pstore,

•   "Manage Linux Persistent Storage",
  

•   "set <addr> <len> [record-size] [console-size] [ftrace-size] [pmsg_size] [ecc-size]\n"
  

•   "- Set pstore reserved memory info, starting at 'addr' for 'len' bytes.\n"
  

•   "  Default length for records is 4K.\n"
  

•   "  'record-size' is the size of one panic or oops record ('dump' type).\n"
  

•   "  'console-size' is the size of the kernel logs record.\n"
  

•   "  'ftrace-size' is the size of the ftrace record(s), this can be a single\n"
  

•   "  record or divided in parts based on number of CPUs.\n"
  

•   "  'pmsg-size' is the size of the user space logs record.\n"
  

•   "  'ecc-size' enables/disables ECC support and specifies ECC buffer size in\n"
  

•   "  bytes (0 disables it, 1 is a special value, means 16 bytes ECC).\n"
  

•   "pstore display [record-type] [nb]\n"
  

•   "- Display existing records in pstore reserved memory. A 'record-type' can\n"
  

•   "  be given to only display records of this kind. 'record-type' can be one\n"
  

•   "  of 'dump', 'console', 'ftrace' or 'user'. For 'dump' and 'ftrace' types,\n"
  

•   "  a 'nb' can be given to only display one record.\n"
  

•   "pstore save <interface> <dev[:part]> <directory-path>\n"
  

•   "- Save existing records in pstore reserved memory under 'directory path'\n"
  

•   "  to partition 'part' on device type 'interface' instance 'dev'.\n"
  

•   "  Filenames are automatically generated, depending on record type, like\n"
  

•   "  in /sys/fs/pstore under Linux.\n"
  

•   "  The 'directory-path' should already exist.\n"
  

+); diff --git a/doc/index.rst b/doc/index.rst index cd98be6cc5..c556cdb607 100644 --- a/doc/index.rst +++ b/doc/index.rst @@ -98,6 +98,13 @@ Android-specific features available in U-Boot.

 android/index

+Command line +------------ +.. toctree::

• :maxdepth: 2
• pstore.rst

• Indices and tables

diff --git a/doc/pstore.rst b/doc/pstore.rst new file mode 100644 index 0000000000..401ba34373 --- /dev/null +++ b/doc/pstore.rst @@ -0,0 +1,68 @@ +.. SPDX-License-Identifier: GPL-2.0+

+PStore command +==============

+Design +------

+Linux PStore and Ramoops modules allow to use memory to pass data from the dying

Please, mention Linux config option PSTORE_RAM here.

+breath of a crashing kernel to its successor. This command allows to read those +records from U-Boot command line.

+Ramoops is an oops/panic logger that writes its logs to RAM before the system +crashes. It works by logging oopses and panics in a circular buffer. Ramoops +needs a system with persistent RAM so that the content of that area can survive +after a restart.

+Ramoops uses a predefined memory area to store the dump.

+Ramoops parameters can be passed as kernel parameters or through Device Tree,

Please, add the node in image_setup_libfdt() as described in Linux's Documentation/device-tree/bindings/reserved-memory/admin-guide/ramoops.rst.

+i.e.::

• ramoops.mem_address=0x30000000 ramoops.mem_size=0x100000 ramoops.record_size=0x2000 ramoops.console_size=0x2000 memmap=0x100000$0x30000000

Using the command line seems to be rather error prone.

+The same values should be set in U-Boot to be able to retrieve the records. +This values can be set at build time in U-Boot configuration file, or at runtime.

+The PStore configuration parameters are:

+======================= =======

• Name Default

+======================= ======= +CMD_PSTORE_ADDR 0x0 +CMD_PSTORE_SIZE 0x0 +CMD_PSTORE_RECORD_SIZE 0x1000 +CMD_PSTORE_CONSOLE_SIZE 0x1000 +CMD_PSTORE_FTRACE_SIZE 0x1000 +CMD_PSTORE_PMSG_SIZE 0x1000 +CMD_PSTORE_ECC_SIZE 0 +======================= =======

Please, describe the requirements on CMD_PSTORE_SIZE. I would assume that is has to be larger than the sum of the other sizes.

+Records sizes should be a power of 2.

Please, mention:

The memory size and the record/console size must be non-zero.

Best regards

Heinrich

+Usage +-----

+Generate kernel crash +~~~~~~~~~~~~~~~~~~~~~

+For test purpose, you can generate a kernel crash by setting reboot timeout to +10 seconds and trigger a panic::

• $ sudo sh -c "echo 1 > /proc/sys/kernel/sysrq"
• $ sudo sh -c "echo 10 > /proc/sys/kernel/panic"
• $ sudo sh -c "echo c > /proc/sysrq-trigger"

+Retrieve logs in U-Boot +~~~~~~~~~~~~~~~~~~~~~~~

+First of all, unless PStore parameters as been set during U-Boot configuration +and match kernel ramoops parameters, it needs to be set using 'pstore set', e.g.::

• => pstore set 0x30000000 0x100000 0x2000 0x2000

+Then all available dumps can be displayed +using::

• => pstore display

+Or saved to an existing directory in an Ext2 or Ext4 partition, e.g. on root +directory of 1st partition of the 2nd MMC::

• => pstore save mmc 1:1 /