cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dm-flakey.rst (2036B)

      1=========
      2dm-flakey
      3=========
      4
      5This target is the same as the linear target except that it exhibits
      6unreliable behaviour periodically.  It's been found useful in simulating
      7failing devices for testing purposes.
      8
      9Starting from the time the table is loaded, the device is available for
     10<up interval> seconds, then exhibits unreliable behaviour for <down
     11interval> seconds, and then this cycle repeats.
     12
     13Also, consider using this in combination with the dm-delay target too,
     14which can delay reads and writes and/or send them to different
     15underlying devices.
     16
     17Table parameters
     18----------------
     19
     20::
     21
     22  <dev path> <offset> <up interval> <down interval> \
     23    [<num_features> [<feature arguments>]]
     24
     25Mandatory parameters:
     26
     27    <dev path>:
     28        Full pathname to the underlying block-device, or a
     29        "major:minor" device-number.
     30    <offset>:
     31        Starting sector within the device.
     32    <up interval>:
     33        Number of seconds device is available.
     34    <down interval>:
     35        Number of seconds device returns errors.
     36
     37Optional feature parameters:
     38
     39  If no feature parameters are present, during the periods of
     40  unreliability, all I/O returns errors.
     41
     42  drop_writes:
     43	All write I/O is silently ignored.
     44	Read I/O is handled correctly.
     45
     46  error_writes:
     47	All write I/O is failed with an error signalled.
     48	Read I/O is handled correctly.
     49
     50  corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
     51	During <down interval>, replace <Nth_byte> of the data of
     52	each matching bio with <value>.
     53
     54    <Nth_byte>:
     55	The offset of the byte to replace.
     56	Counting starts at 1, to replace the first byte.
     57    <direction>:
     58	Either 'r' to corrupt reads or 'w' to corrupt writes.
     59	'w' is incompatible with drop_writes.
     60    <value>:
     61	The value (from 0-255) to write.
     62    <flags>:
     63	Perform the replacement only if bio->bi_opf has all the
     64	selected flags set.
     65
     66Examples:
     67
     68Replaces the 32nd byte of READ bios with the value 1::
     69
     70  corrupt_bio_byte 32 r 1 0
     71
     72Replaces the 224th byte of REQ_META (=32) bios with the value 0::
     73
     74  corrupt_bio_byte 224 w 0 32