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Commit 29e4936d authored by Huang Yiwei's avatar Huang Yiwei
Browse files

pstore: Add support to cached pages 



Add new DT option to support cached pages, this can improve the
performance.

Change-Id: Ic13760ed127a1dcd6dd21baa06d8ada7c9f16313
Signed-off-by: default avatarHuang Yiwei <hyiwei@codeaurora.org>
parent 4027c201

Documentation/admin-guide/ramoops.rst

+4 −2
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ Ramoops oops/panic logger 


Sergiu Iordache <sergiu@chromium.org>



Updated: 17 November 2011

Updated: 10 July 2020



Introduction

------------
@@ -29,7 +29,9 @@ mapping to pgprot_writecombine. Setting ``mem_type=1`` attempts to use 
``pgprot_noncached``, which only works on some platforms. This is because pstore

depends on atomic operations. At least on ARM, pgprot_noncached causes the

memory to be mapped strongly ordered, and atomic operations on strongly ordered

memory are implementation defined, and won't work on many ARMs such as omaps.

memory are implementation defined, and won't work on many ARMs such as omaps. Setting

``mem_type=2`` attempts to treat the memory region as normal memory, which enables

full cache on it. This can improve the performance.



The memory area is divided into ``record_size`` chunks (also rounded down to

power of two) and each oops/panic writes a ``record_size`` chunk of

fs/pstore/ram.c

+2 −1
Original line number Diff line number Diff line
@@ -686,6 +686,7 @@ static int ramoops_parse_dt(struct platform_device *pdev, 


	pdata->mem_size = resource_size(res);

	pdata->mem_address = res->start;

	if (of_property_read_u32(of_node, "mem-type", &pdata->mem_type))

		pdata->mem_type = of_property_read_bool(of_node, "unbuffered");

	pdata->dump_oops = !of_property_read_bool(of_node, "no-dump-oops");

fs/pstore/ram_core.c

+6 −1
Original line number Diff line number Diff line
@@ -37,6 +37,9 @@ struct persistent_ram_buffer { 
	uint8_t     data[0];

};



#define MEM_TYPE_WCOMBINE	0

#define MEM_TYPE_NONCACHED	1

#define MEM_TYPE_NORMAL		2

#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */



static inline size_t buffer_size(struct persistent_ram_zone *prz)
@@ -411,8 +414,10 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size, 
	page_start = start - offset_in_page(start);

	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);



	if (memtype)

	if (memtype == MEM_TYPE_NONCACHED)

		prot = pgprot_noncached(PAGE_KERNEL);

	else if (memtype == MEM_TYPE_NORMAL)

		prot = PAGE_KERNEL;

	else

		prot = pgprot_writecombine(PAGE_KERNEL);