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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-12 11:34:13 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-12 11:34:13 -0800 |
| commit | 6ce4436c9cbe903af935291aa219fd6f4c85722d (patch) | |
| tree | 43dedf78042c619d8b5b0a77d6937eb22805d874 /Documentation | |
| parent | bdeb03cada1c305346505c48e5b1dab37e9acc4e (diff) | |
| parent | 027bc8b08242c59e19356b4b2c189f2d849ab660 (diff) | |
| download | linux-6ce4436c9cbe903af935291aa219fd6f4c85722d.tar.bz2 | |
Merge tag 'please-pull-morepstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux
Pull pstore update #2 from Tony Luck:
"Couple of pstore-ram enhancements to allow use of different memory
attributes"
* tag 'please-pull-morepstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
pstore-ram: Allow optional mapping with pgprot_noncached
pstore-ram: Fix hangs by using write-combine mappings
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ramoops.txt | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt index 69b3cac4749d..5d8675615e59 100644 --- a/Documentation/ramoops.txt +++ b/Documentation/ramoops.txt @@ -14,11 +14,19 @@ survive after a restart. 1. Ramoops concepts -Ramoops uses a predefined memory area to store the dump. The start and size of -the memory area are set using two variables: +Ramoops uses a predefined memory area to store the dump. The start and size +and type of the memory area are set using three variables: * "mem_address" for the start * "mem_size" for the size. The memory size will be rounded down to a power of two. + * "mem_type" to specifiy if the memory type (default is pgprot_writecombine). + +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 +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. 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 @@ -55,6 +63,7 @@ Setting the ramoops parameters can be done in 2 different manners: static struct ramoops_platform_data ramoops_data = { .mem_size = <...>, .mem_address = <...>, + .mem_type = <...>, .record_size = <...>, .dump_oops = <...>, .ecc = <...>, |