aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/kernel-parameters.txt
diff options
context:
space:
mode:
authorJames Morris <jmorris@namei.org>2008-11-05 18:12:34 -0500
committerJames Morris <jmorris@namei.org>2008-11-05 18:12:34 -0500
commite21e696edb498c7f7eed42ba3096f6bbe13927b6 (patch)
tree73b0bc28e45b0268f05c4b384a17bfb2140a73bc /Documentation/kernel-parameters.txt
parent2f99db28af90957271a6448479c3e492ccf7c697 (diff)
parent75fa67706cce5272bcfc51ed646f2da21f3bdb6e (diff)
Merge branch 'master' into next
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt184
1 files changed, 148 insertions, 36 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 329dcabe4c5e..1bbcaa8982b6 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -100,7 +100,8 @@ parameter is applicable:
100 X86-32 X86-32, aka i386 architecture is enabled. 100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled. 101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in 102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt . 103 Documentation/x86/x86_64/boot-options.txt .
104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
104 105
105In addition, the following text indicates that the option: 106In addition, the following text indicates that the option:
106 107
@@ -111,10 +112,10 @@ In addition, the following text indicates that the option:
111Parameters denoted with BOOT are actually interpreted by the boot 112Parameters denoted with BOOT are actually interpreted by the boot
112loader, and have no meaning to the kernel directly. 113loader, and have no meaning to the kernel directly.
113Do not modify the syntax of boot loader parameters without extreme 114Do not modify the syntax of boot loader parameters without extreme
114need or coordination with <Documentation/i386/boot.txt>. 115need or coordination with <Documentation/x86/i386/boot.txt>.
115 116
116There are also arch-specific kernel-parameters not documented here. 117There are also arch-specific kernel-parameters not documented here.
117See for example <Documentation/x86_64/boot-options.txt>. 118See for example <Documentation/x86/x86_64/boot-options.txt>.
118 119
119Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120a trailing = on the name of any parameter states that that parameter will 121a trailing = on the name of any parameter states that that parameter will
@@ -217,20 +218,47 @@ and is between 256 and 4096 characters. It is defined in the file
217 acpi.debug_level= [HW,ACPI] 218 acpi.debug_level= [HW,ACPI]
218 Format: <int> 219 Format: <int>
219 Each bit of the <int> indicates an ACPI debug level, 220 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time 221 which corresponds to the level in an ACPI_DEBUG_PRINT
221 debugging. After system has booted up, it can be set 222 statement. After system has booted up, this mask
222 via /sys/module/acpi/parameters/debug_level. 223 can be set via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output. 224
224 Available bits (add the numbers together) to enable different 225 CONFIG_ACPI_DEBUG must be enabled for this to produce
225 debug output levels of the ACPI subsystem: 226 any output. The number can be in decimal or prefixed
226 0x01 error 0x02 warn 0x04 init 0x08 debug object 227 with 0x in hex. Some of these options produce so much
227 0x10 info 0x20 init names 0x40 parse 0x80 load 228 output that the system is unusable.
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region 229
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects 230 The following global components are defined by the
230 0x10000 resources 0x20000 user requests 0x40000 package. 231 ACPI CA:
231 The number can be in decimal or prefixed with 0x in hex. 232 0x01 error
232 Warning: Many of these options can produce a lot of 233 0x02 warn
233 output and make your system unusable. Be very careful. 234 0x04 init
235 0x08 debug object
236 0x10 info
237 0x20 init names
238 0x40 parse
239 0x80 load
240 0x100 dispatch
241 0x200 execute
242 0x400 names
243 0x800 operation region
244 0x1000 bfield
245 0x2000 tables
246 0x4000 values
247 0x8000 objects
248 0x10000 resources
249 0x20000 user requests
250 0x40000 package
251 The number can be in decimal or prefixed with 0x in hex.
252 Warning: Many of these options can produce a lot of
253 output and make your system unusable. Be very careful.
254
255 acpi.power_nocheck= [HW,ACPI]
256 Format: 1/0 enable/disable the check of power state.
257 On some bogus BIOS the _PSC object/_STA object of
258 power resource can't return the correct device power
259 state. In such case it is unneccessary to check its
260 power state again in power transition.
261 1 : disable the power state check
234 262
235 acpi_pm_good [X86-32,X86-64] 263 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel 264 Override the pmtimer bug detection: force the kernel
@@ -284,6 +312,11 @@ and is between 256 and 4096 characters. It is defined in the file
284 isolate - enable device isolation (each device, as far 312 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection 313 as possible, will get its own protection
286 domain) 314 domain)
315 fullflush - enable flushing of IO/TLB entries when
316 they are unmapped. Otherwise they are
317 flushed before they will be reused, which
318 is a lot of faster
319
287 amd_iommu_size= [HW,X86-64] 320 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU 321 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are: 322 driver. Possible values are:
@@ -653,11 +686,12 @@ and is between 256 and 4096 characters. It is defined in the file
653 earlyprintk= [X86-32,X86-64,SH,BLACKFIN] 686 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
654 earlyprintk=vga 687 earlyprintk=vga
655 earlyprintk=serial[,ttySn[,baudrate]] 688 earlyprintk=serial[,ttySn[,baudrate]]
689 earlyprintk=dbgp
656 690
657 Append ",keep" to not disable it when the real console 691 Append ",keep" to not disable it when the real console
658 takes over. 692 takes over.
659 693
660 Only vga or serial at a time, not both. 694 Only vga or serial or usb debug port at a time.
661 695
662 Currently only ttyS0 and ttyS1 are supported. 696 Currently only ttyS0 and ttyS1 are supported.
663 697
@@ -684,7 +718,7 @@ and is between 256 and 4096 characters. It is defined in the file
684 See Documentation/block/as-iosched.txt and 718 See Documentation/block/as-iosched.txt and
685 Documentation/block/deadline-iosched.txt for details. 719 Documentation/block/deadline-iosched.txt for details.
686 720
687 elfcorehdr= [X86-32, X86_64] 721 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
688 Specifies physical address of start of kernel core 722 Specifies physical address of start of kernel core
689 image elf header. Generally kexec loader will 723 image elf header. Generally kexec loader will
690 pass this option to capture kernel. 724 pass this option to capture kernel.
@@ -790,6 +824,9 @@ and is between 256 and 4096 characters. It is defined in the file
790 Defaults to the default architecture's huge page size 824 Defaults to the default architecture's huge page size
791 if not specified. 825 if not specified.
792 826
827 hlt [BUGS=ARM,SH]
828
829 i8042.debug [HW] Toggle i8042 debug mode
793 i8042.direct [HW] Put keyboard port into non-translated mode 830 i8042.direct [HW] Put keyboard port into non-translated mode
794 i8042.dumbkbd [HW] Pretend that controller can only read data from 831 i8042.dumbkbd [HW] Pretend that controller can only read data from
795 keyboard and cannot control its state 832 keyboard and cannot control its state
@@ -1014,6 +1051,10 @@ and is between 256 and 4096 characters. It is defined in the file
1014 (only serial suported for now) 1051 (only serial suported for now)
1015 Format: <serial_device>[,baud] 1052 Format: <serial_device>[,baud]
1016 1053
1054 kmac= [MIPS] korina ethernet MAC address.
1055 Configure the RouterBoard 532 series on-chip
1056 Ethernet adapter MAC address.
1057
1017 l2cr= [PPC] 1058 l2cr= [PPC]
1018 1059
1019 l3cr= [PPC] 1060 l3cr= [PPC]
@@ -1181,7 +1222,7 @@ and is between 256 and 4096 characters. It is defined in the file
1181 1222
1182 mce [X86-32] Machine Check Exception 1223 mce [X86-32] Machine Check Exception
1183 1224
1184 mce=option [X86-64] See Documentation/x86_64/boot-options.txt 1225 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1185 1226
1186 md= [HW] RAID subsystems devices and level 1227 md= [HW] RAID subsystems devices and level
1187 See Documentation/md.txt. 1228 See Documentation/md.txt.
@@ -1200,6 +1241,10 @@ and is between 256 and 4096 characters. It is defined in the file
1200 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 1241 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1201 memory. 1242 memory.
1202 1243
1244 memchunk=nn[KMG]
1245 [KNL,SH] Allow user to override the default size for
1246 per-device physically contiguous DMA buffers.
1247
1203 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact 1248 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1204 E820 memory map, as specified by the user. 1249 E820 memory map, as specified by the user.
1205 Such memmap=exactmap lines can be constructed based on 1250 Such memmap=exactmap lines can be constructed based on
@@ -1222,6 +1267,29 @@ and is between 256 and 4096 characters. It is defined in the file
1222 or 1267 or
1223 memmap=0x10000$0x18690000 1268 memmap=0x10000$0x18690000
1224 1269
1270 memory_corruption_check=0/1 [X86]
1271 Some BIOSes seem to corrupt the first 64k of
1272 memory when doing things like suspend/resume.
1273 Setting this option will scan the memory
1274 looking for corruption. Enabling this will
1275 both detect corruption and prevent the kernel
1276 from using the memory being corrupted.
1277 However, its intended as a diagnostic tool; if
1278 repeatable BIOS-originated corruption always
1279 affects the same memory, you can use memmap=
1280 to prevent the kernel from using that memory.
1281
1282 memory_corruption_check_size=size [X86]
1283 By default it checks for corruption in the low
1284 64k, making this memory unavailable for normal
1285 use. Use this parameter to scan for
1286 corruption in more or less memory.
1287
1288 memory_corruption_check_period=seconds [X86]
1289 By default it checks for corruption every 60
1290 seconds. Use this parameter to check at some
1291 other rate. 0 disables periodic checking.
1292
1225 memtest= [KNL,X86] Enable memtest 1293 memtest= [KNL,X86] Enable memtest
1226 Format: <integer> 1294 Format: <integer>
1227 range: 0,4 : pattern number 1295 range: 0,4 : pattern number
@@ -1359,6 +1427,8 @@ and is between 256 and 4096 characters. It is defined in the file
1359 1427
1360 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1428 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1361 1429
1430 nodsp [SH] Disable hardware DSP at boot time.
1431
1362 noefi [X86-32,X86-64] Disable EFI runtime services support. 1432 noefi [X86-32,X86-64] Disable EFI runtime services support.
1363 1433
1364 noexec [IA-64] 1434 noexec [IA-64]
@@ -1375,13 +1445,15 @@ and is between 256 and 4096 characters. It is defined in the file
1375 noexec32=off: disable non-executable mappings 1445 noexec32=off: disable non-executable mappings
1376 read implies executable mappings 1446 read implies executable mappings
1377 1447
1448 nofpu [SH] Disable hardware FPU at boot time.
1449
1378 nofxsr [BUGS=X86-32] Disables x86 floating point extended 1450 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1379 register save and restore. The kernel will only save 1451 register save and restore. The kernel will only save
1380 legacy floating-point registers on task switch. 1452 legacy floating-point registers on task switch.
1381 1453
1382 noclflush [BUGS=X86] Don't use the CLFLUSH instruction 1454 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1383 1455
1384 nohlt [BUGS=ARM] 1456 nohlt [BUGS=ARM,SH]
1385 1457
1386 no-hlt [BUGS=X86-32] Tells the kernel that the hlt 1458 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1387 instruction doesn't work correctly and not to 1459 instruction doesn't work correctly and not to
@@ -1419,6 +1491,12 @@ and is between 256 and 4096 characters. It is defined in the file
1419 1491
1420 nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 1492 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1421 1493
1494 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1495
1496 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1497 default x2apic cluster mode on platforms
1498 supporting x2apic.
1499
1422 noltlbs [PPC] Do not use large page/tlb entries for kernel 1500 noltlbs [PPC] Do not use large page/tlb entries for kernel
1423 lowmem mapping on PPC40x. 1501 lowmem mapping on PPC40x.
1424 1502
@@ -1538,7 +1616,7 @@ and is between 256 and 4096 characters. It is defined in the file
1538 See also Documentation/paride.txt. 1616 See also Documentation/paride.txt.
1539 1617
1540 pci=option[,option...] [PCI] various PCI subsystem options: 1618 pci=option[,option...] [PCI] various PCI subsystem options:
1541 off [X86-32] don't probe for the PCI bus 1619 off [X86] don't probe for the PCI bus
1542 bios [X86-32] force use of PCI BIOS, don't access 1620 bios [X86-32] force use of PCI BIOS, don't access
1543 the hardware directly. Use this if your machine 1621 the hardware directly. Use this if your machine
1544 has a non-standard PCI host bridge. 1622 has a non-standard PCI host bridge.
@@ -1546,9 +1624,9 @@ and is between 256 and 4096 characters. It is defined in the file
1546 hardware access methods are allowed. Use this 1624 hardware access methods are allowed. Use this
1547 if you experience crashes upon bootup and you 1625 if you experience crashes upon bootup and you
1548 suspect they are caused by the BIOS. 1626 suspect they are caused by the BIOS.
1549 conf1 [X86-32] Force use of PCI Configuration 1627 conf1 [X86] Force use of PCI Configuration
1550 Mechanism 1. 1628 Mechanism 1.
1551 conf2 [X86-32] Force use of PCI Configuration 1629 conf2 [X86] Force use of PCI Configuration
1552 Mechanism 2. 1630 Mechanism 2.
1553 noaer [PCIE] If the PCIEAER kernel config parameter is 1631 noaer [PCIE] If the PCIEAER kernel config parameter is
1554 enabled, this kernel boot option can be used to 1632 enabled, this kernel boot option can be used to
@@ -1568,37 +1646,37 @@ and is between 256 and 4096 characters. It is defined in the file
1568 this option if the kernel is unable to allocate 1646 this option if the kernel is unable to allocate
1569 IRQs or discover secondary PCI buses on your 1647 IRQs or discover secondary PCI buses on your
1570 motherboard. 1648 motherboard.
1571 rom [X86-32] Assign address space to expansion ROMs. 1649 rom [X86] Assign address space to expansion ROMs.
1572 Use with caution as certain devices share 1650 Use with caution as certain devices share
1573 address decoders between ROMs and other 1651 address decoders between ROMs and other
1574 resources. 1652 resources.
1575 norom [X86-32,X86_64] Do not assign address space to 1653 norom [X86] Do not assign address space to
1576 expansion ROMs that do not already have 1654 expansion ROMs that do not already have
1577 BIOS assigned address ranges. 1655 BIOS assigned address ranges.
1578 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be 1656 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1579 assigned automatically to PCI devices. You can 1657 assigned automatically to PCI devices. You can
1580 make the kernel exclude IRQs of your ISA cards 1658 make the kernel exclude IRQs of your ISA cards
1581 this way. 1659 this way.
1582 pirqaddr=0xAAAAA [X86-32] Specify the physical address 1660 pirqaddr=0xAAAAA [X86] Specify the physical address
1583 of the PIRQ table (normally generated 1661 of the PIRQ table (normally generated
1584 by the BIOS) if it is outside the 1662 by the BIOS) if it is outside the
1585 F0000h-100000h range. 1663 F0000h-100000h range.
1586 lastbus=N [X86-32] Scan all buses thru bus #N. Can be 1664 lastbus=N [X86] Scan all buses thru bus #N. Can be
1587 useful if the kernel is unable to find your 1665 useful if the kernel is unable to find your
1588 secondary buses and you want to tell it 1666 secondary buses and you want to tell it
1589 explicitly which ones they are. 1667 explicitly which ones they are.
1590 assign-busses [X86-32] Always assign all PCI bus 1668 assign-busses [X86] Always assign all PCI bus
1591 numbers ourselves, overriding 1669 numbers ourselves, overriding
1592 whatever the firmware may have done. 1670 whatever the firmware may have done.
1593 usepirqmask [X86-32] Honor the possible IRQ mask stored 1671 usepirqmask [X86] Honor the possible IRQ mask stored
1594 in the BIOS $PIR table. This is needed on 1672 in the BIOS $PIR table. This is needed on
1595 some systems with broken BIOSes, notably 1673 some systems with broken BIOSes, notably
1596 some HP Pavilion N5400 and Omnibook XE3 1674 some HP Pavilion N5400 and Omnibook XE3
1597 notebooks. This will have no effect if ACPI 1675 notebooks. This will have no effect if ACPI
1598 IRQ routing is enabled. 1676 IRQ routing is enabled.
1599 noacpi [X86-32] Do not use ACPI for IRQ routing 1677 noacpi [X86] Do not use ACPI for IRQ routing
1600 or for PCI scanning. 1678 or for PCI scanning.
1601 use_crs [X86-32] Use _CRS for PCI resource 1679 use_crs [X86] Use _CRS for PCI resource
1602 allocation. 1680 allocation.
1603 routeirq Do IRQ routing for all PCI devices. 1681 routeirq Do IRQ routing for all PCI devices.
1604 This is normally done in pci_enable_device(), 1682 This is normally done in pci_enable_device(),
@@ -1627,6 +1705,12 @@ and is between 256 and 4096 characters. It is defined in the file
1627 reserved for the CardBus bridge's memory 1705 reserved for the CardBus bridge's memory
1628 window. The default value is 64 megabytes. 1706 window. The default value is 64 megabytes.
1629 1707
1708 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1709 Management.
1710 off Disable ASPM.
1711 force Enable ASPM even on devices that claim not to support it.
1712 WARNING: Forcing ASPM on may cause system lockups.
1713
1630 pcmv= [HW,PCMCIA] BadgePAD 4 1714 pcmv= [HW,PCMCIA] BadgePAD 4
1631 1715
1632 pd. [PARIDE] 1716 pd. [PARIDE]
@@ -1644,7 +1728,7 @@ and is between 256 and 4096 characters. It is defined in the file
1644 See Documentation/paride.txt. 1728 See Documentation/paride.txt.
1645 1729
1646 pirq= [SMP,APIC] Manual mp-table setup 1730 pirq= [SMP,APIC] Manual mp-table setup
1647 See Documentation/i386/IO-APIC.txt. 1731 See Documentation/x86/i386/IO-APIC.txt.
1648 1732
1649 plip= [PPT,NET] Parallel port network link 1733 plip= [PPT,NET] Parallel port network link
1650 Format: { parport<nr> | timid | 0 } 1734 Format: { parport<nr> | timid | 0 }
@@ -1654,6 +1738,10 @@ and is between 256 and 4096 characters. It is defined in the file
1654 Override pmtimer IOPort with a hex value. 1738 Override pmtimer IOPort with a hex value.
1655 e.g. pmtmr=0x508 1739 e.g. pmtmr=0x508
1656 1740
1741 pnp.debug [PNP]
1742 Enable PNP debug messages. This depends on the
1743 CONFIG_PNP_DEBUG_MESSAGES option.
1744
1657 pnpacpi= [ACPI] 1745 pnpacpi= [ACPI]
1658 { off } 1746 { off }
1659 1747
@@ -1674,6 +1762,11 @@ and is between 256 and 4096 characters. It is defined in the file
1674 autoconfiguration. 1762 autoconfiguration.
1675 Ranges are in pairs (memory base and size). 1763 Ranges are in pairs (memory base and size).
1676 1764
1765 dynamic_printk
1766 Enables pr_debug()/dev_dbg() calls if
1767 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1768 be switched on/off via <debugfs>/dynamic_printk/modules
1769
1677 print-fatal-signals= 1770 print-fatal-signals=
1678 [KNL] debug: print fatal signals 1771 [KNL] debug: print fatal signals
1679 print-fatal-signals=1: print segfault info to 1772 print-fatal-signals=1: print segfault info to
@@ -2146,7 +2239,7 @@ and is between 256 and 4096 characters. It is defined in the file
2146 2239
2147 thermal.crt= [HW,ACPI] 2240 thermal.crt= [HW,ACPI]
2148 -1: disable all critical trip points in all thermal zones 2241 -1: disable all critical trip points in all thermal zones
2149 <degrees C>: lower all critical trip points 2242 <degrees C>: override all critical trip points
2150 2243
2151 thermal.nocrt= [HW,ACPI] 2244 thermal.nocrt= [HW,ACPI]
2152 Set to disable actions on ACPI thermal zone 2245 Set to disable actions on ACPI thermal zone
@@ -2208,6 +2301,25 @@ and is between 256 and 4096 characters. It is defined in the file
2208 autosuspended. Devices for which the delay is set 2301 autosuspended. Devices for which the delay is set
2209 to a negative value won't be autosuspended at all. 2302 to a negative value won't be autosuspended at all.
2210 2303
2304 usbcore.usbfs_snoop=
2305 [USB] Set to log all usbfs traffic (default 0 = off).
2306
2307 usbcore.blinkenlights=
2308 [USB] Set to cycle leds on hubs (default 0 = off).
2309
2310 usbcore.old_scheme_first=
2311 [USB] Start with the old device initialization
2312 scheme (default 0 = off).
2313
2314 usbcore.use_both_schemes=
2315 [USB] Try the other device initialization scheme
2316 if the first one fails (default 1 = enabled).
2317
2318 usbcore.initial_descriptor_timeout=
2319 [USB] Specifies timeout for the initial 64-byte
2320 USB_REQ_GET_DESCRIPTOR request in milliseconds
2321 (default 5000 = 5.0 seconds).
2322
2211 usbhid.mousepoll= 2323 usbhid.mousepoll=
2212 [USBHID] The interval which mice are to be polled at. 2324 [USBHID] The interval which mice are to be polled at.
2213 2325
@@ -2231,7 +2343,7 @@ and is between 256 and 4096 characters. It is defined in the file
2231 See Documentation/fb/modedb.txt. 2343 See Documentation/fb/modedb.txt.
2232 2344
2233 vga= [BOOT,X86-32] Select a particular video mode 2345 vga= [BOOT,X86-32] Select a particular video mode
2234 See Documentation/i386/boot.txt and 2346 See Documentation/x86/i386/boot.txt and
2235 Documentation/svga.txt. 2347 Documentation/svga.txt.
2236 Use vga=ask for menu. 2348 Use vga=ask for menu.
2237 This is actually a boot loader parameter; the value is 2349 This is actually a boot loader parameter; the value is