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authorTejun Heo <htejun@gmail.com>2008-02-12 19:15:09 -0500
committerJeff Garzik <jeff@garzik.org>2008-02-20 12:12:28 -0500
commit332673257056d8be8a69d759eda90a799af5472d (patch)
treeb2ff47054b6424f70a6c10bcffd47f2bdd70e4c8 /Documentation
parent0fca0d6f2ce3336022a22bc7fc2e009e599e63a4 (diff)
libata: implement libata.force module parameter
This patch implements libata.force module parameter which can selectively override ATA port, link and device configurations including cable type, SATA PHY SPD limit, transfer mode and NCQ. For example, you can say "use 1.5Gbps for all fan-out ports attached to the second port but allow 3.0Gbps for the PMP device itself, oh, the device attached to the third fan-out port chokes on NCQ and shouldn't go over UDMA4" by the following. libata.force=2:1.5g,2.15:3.0g,2.03:noncq,udma4 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt35
1 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7278295f94d2..9a5b6658c65e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -950,6 +950,41 @@ and is between 256 and 4096 characters. It is defined in the file
950 when set. 950 when set.
951 Format: <int> 951 Format: <int>
952 952
953 libata.force= [LIBATA] Force configurations. The format is comma
954 separated list of "[ID:]VAL" where ID is
955 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
956 matching port, link or device. Basically, it matches
957 the ATA ID string printed on console by libata. If
958 the whole ID part is omitted, the last PORT and DEVICE
959 values are used. If ID hasn't been specified yet, the
960 configuration applies to all ports, links and devices.
961
962 If only DEVICE is omitted, the parameter applies to
963 the port and all links and devices behind it. DEVICE
964 number of 0 either selects the first device or the
965 first fan-out link behind PMP device. It does not
966 select the host link. DEVICE number of 15 selects the
967 host link and device attached to it.
968
969 The VAL specifies the configuration to force. As long
970 as there's no ambiguity shortcut notation is allowed.
971 For example, both 1.5 and 1.5G would work for 1.5Gbps.
972 The following configurations can be forced.
973
974 * Cable type: 40c, 80c, short40c, unk, ign or sata.
975 Any ID with matching PORT is used.
976
977 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
978
979 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
980 udma[/][16,25,33,44,66,100,133] notation is also
981 allowed.
982
983 * [no]ncq: Turn on or off NCQ.
984
985 If there are multiple matching configurations changing
986 the same attribute, the last one is used.
987
953 load_ramdisk= [RAM] List of ramdisks to load from floppy 988 load_ramdisk= [RAM] List of ramdisks to load from floppy
954 See Documentation/ramdisk.txt. 989 See Documentation/ramdisk.txt.
955 990