On 2/10/21 11:40 AM, Randy Dunlap wrote:
> Hi--
>
> On 2/10/21 6:52 AM, Mukesh Ojha wrote:
>> There could be a sceanario where we define some region
>
> scenario
>
>> in normal memory and use them store to logs which is later
>> retrieved by bootloader during warm reset.
>>
>> In this scenario, we wanted to treat this memory as normal
>> cacheable memory instead of default behaviour which
>> is an overhead. Making it cacheable could improve
>> performance.
>>
>> This commit gives control to change mem_type from Device
>> tree, and also documents the value for normal memory.
>>
>> Signed-off-by: Huang Yiwei <hyi...@codeaurora.org>
>> Signed-off-by: Mukesh Ojha <mo...@codeaurora.org>
>> ---
>> Documentation/admin-guide/ramoops.rst | 4 +++-
>> fs/pstore/ram.c | 1 +
>> fs/pstore/ram_core.c | 10 ++++++++--
>> 3 files changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/ramoops.rst
>> b/Documentation/admin-guide/ramoops.rst
>> index b0a1ae7..8f107d8 100644
>> --- a/Documentation/admin-guide/ramoops.rst
>> +++ b/Documentation/admin-guide/ramoops.rst
>> @@ -3,7 +3,7 @@ Ramoops oops/panic logger
>>
>> Sergiu Iordache <ser...@chromium.org>
>>
>> -Updated: 17 November 2011
>> +Updated: 10 Feb 2021
>>
>> Introduction
>> ------------
>> @@ -30,6 +30,8 @@ mapping to pgprot_writecombine. Setting ``mem_type=1``
>> attempts to use
>> 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.
>> +Setting ``mem_type=2`` attempts to treat the memory region as normal memory,
>
> Does "mem_type=" work? or does it need to be "mem-type=", as below?
> I.e., do both of them work?
>
Ah yes, as documented:
"Hyphens (dashes) and underscores are equivalent in parameter names,"
thanks.
>> +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 kmesg dump writes a ``record_size`` chunk of
>> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
>> index ca6d8a8..b262c57 100644
>> --- a/fs/pstore/ram.c
>> +++ b/fs/pstore/ram.c
>> @@ -666,6 +666,7 @@ static int ramoops_parse_dt(struct platform_device *pdev,
>> field = value; \
>> }
>>
>> + parse_u32("mem-type", pdata->record_size, pdata->mem_type);
>
> here^^^^^^^^^^
--
~Randy
