diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 39 | ||||
| -rw-r--r-- | Documentation/powerpc/mpc52xx-device-tree-bindings.txt | 189 | ||||
| -rw-r--r-- | Documentation/s390/CommonIO | 4 | ||||
| -rw-r--r-- | Documentation/s390/Debugging390.txt | 38 | ||||
| -rw-r--r-- | Documentation/s390/cds.txt | 12 | ||||
| -rw-r--r-- | Documentation/s390/crypto/crypto-API.txt | 6 | ||||
| -rw-r--r-- | Documentation/s390/s390dbf.txt | 8 |
7 files changed, 262 insertions, 34 deletions
diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index 4ac2d641fcb6..b3bd36668db3 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -6,6 +6,8 @@ IBM Corp. (c) 2005 Becky Bruce <becky.bruce at freescale.com>, Freescale Semiconductor, FSL SOC and 32-bit additions +(c) 2006 MontaVista Software, Inc. + Flash chip node definition May 18, 2005: Rev 0.1 - Initial draft, no chapter III yet. @@ -1693,6 +1695,43 @@ platforms are moved over to use the flattened-device-tree model. }; }; + g) Flash chip nodes + + Flash chips (Memory Technology Devices) are often used for solid state + file systems on embedded devices. + + Required properties: + + - device_type : has to be "rom" + - compatible : Should specify what this ROM device is compatible with + (i.e. "onenand"). Currently, this is most likely to be "direct-mapped" + (which corresponds to the MTD physmap mapping driver). + - regs : Offset and length of the register set (or memory mapping) for + the device. + + Recommended properties : + + - bank-width : Width of the flash data bus in bytes. Required + for the NOR flashes (compatible == "direct-mapped" and others) ONLY. + - partitions : Several pairs of 32-bit values where the first value is + partition's offset from the start of the device and the second one is + partition size in bytes with LSB used to signify a read only + partititon (so, the parition size should always be an even number). + - partition-names : The list of concatenated zero terminated strings + representing the partition names. + + Example: + + flash@ff000000 { + device_type = "rom"; + compatible = "direct-mapped"; + regs = <ff000000 01000000>; + bank-width = <4>; + partitions = <00000000 00f80000 + 00f80000 00080001>; + partition-names = "fs\0firmware"; + }; + More devices will be defined as this spec matures. diff --git a/Documentation/powerpc/mpc52xx-device-tree-bindings.txt b/Documentation/powerpc/mpc52xx-device-tree-bindings.txt new file mode 100644 index 000000000000..d077d764f82b --- /dev/null +++ b/Documentation/powerpc/mpc52xx-device-tree-bindings.txt @@ -0,0 +1,189 @@ +MPC52xx Device Tree Bindings +---------------------------- + +(c) 2006 Secret Lab Technologies Ltd +Grant Likely <grant.likely at secretlab.ca> + +I - Introduction +================ +Boards supported by the arch/powerpc architecture require device tree be +passed by the boot loader to the kernel at boot time. The device tree +describes what devices are present on the board and how they are +connected. The device tree can either be passed as a binary blob (as +described in Documentation/powerpc/booting-without-of.txt), or passed +by Open Firmare (IEEE 1275) compatible firmware using an OF compatible +client interface API. + +This document specifies the requirements on the device-tree for mpc52xx +based boards. These requirements are above and beyond the details +specified in either the OpenFirmware spec or booting-without-of.txt + +All new mpc52xx-based boards are expected to match this document. In +cases where this document is not sufficient to support a new board port, +this document should be updated as part of adding the new board support. + +II - Philosophy +=============== +The core of this document is naming convention. The whole point of +defining this convention is to reduce or eliminate the number of +special cases required to support a 52xx board. If all 52xx boards +follow the same convention, then generic 52xx support code will work +rather than coding special cases for each new board. + +This section tries to capture the thought process behind why the naming +convention is what it is. + +1. Node names +------------- +There is strong convention/requirements already established for children +of the root node. 'cpus' describes the processor cores, 'memory' +describes memory, and 'chosen' provides boot configuration. Other nodes +are added to describe devices attached to the processor local bus. +Following convention already established with other system-on-chip +processors, MPC52xx boards must have an 'soc5200' node as a child of the +root node. + +The soc5200 node holds child nodes for all on chip devices. Child nodes +are typically named after the configured function. ie. the FEC node is +named 'ethernet', and a PSC in uart mode is named 'serial'. + +2. device_type property +----------------------- +similar to the node name convention above; the device_type reflects the +configured function of a device. ie. 'serial' for a uart and 'spi' for +an spi controller. However, while node names *should* reflect the +configured function, device_type *must* match the configured function +exactly. + +3. compatible property +---------------------- +Since device_type isn't enough to match devices to drivers, there also +needs to be a naming convention for the compatible property. Compatible +is an list of device descriptions sorted from specific to generic. For +the mpc52xx, the required format for each compatible value is +<chip>-<device>[-<mode>]. At the minimum, the list shall contain two +items; the first specifying the exact chip, and the second specifying +mpc52xx for the chip. + +ie. ethernet on mpc5200b: compatible = "mpc5200b-ethernet\0mpc52xx-ethernet" + +The idea here is that most drivers will match to the most generic field +in the compatible list (mpc52xx-*), but can also test the more specific +field for enabling bug fixes or extra features. + +Modal devices, like PSCs, also append the configured function to the +end of the compatible field. ie. A PSC in i2s mode would specify +"mpc52xx-psc-i2s", not "mpc52xx-i2s". This convention is chosen to +avoid naming conflicts with non-psc devices providing the same +function. For example, "mpc52xx-spi" and "mpc52xx-psc-spi" describe +the mpc5200 simple spi device and a PSC spi mode respectively. + +If the soc device is more generic and present on other SOCs, the +compatible property can specify the more generic device type also. + +ie. mscan: compatible = "mpc5200-mscan\0mpc52xx-mscan\0fsl,mscan"; + +At the time of writing, exact chip may be either 'mpc5200' or +'mpc5200b'. + +Device drivers should always try to match as generically as possible. + +III - Structure +=============== +The device tree for an mpc52xx board follows the structure defined in +booting-without-of.txt with the following additional notes: + +0) the root node +---------------- +Typical root description node; see booting-without-of + +1) The cpus node +---------------- +The cpus node follows the basic layout described in booting-without-of. +The bus-frequency property holds the XLB bus frequency +The clock-frequency property holds the core frequency + +2) The memory node +------------------ +Typical memory description node; see booting-without-of. + +3) The soc5200 node +------------------- +This node describes the on chip SOC peripherals. Every mpc52xx based +board will have this node, and as such there is a common naming +convention for SOC devices. + +Required properties: +name type description +---- ---- ----------- +device_type string must be "soc" +ranges int should be <0 baseaddr baseaddr+10000> +reg int must be <baseaddr 10000> + +Recommended properties: +name type description +---- ---- ----------- +compatible string should be "<chip>-soc\0mpc52xx-soc" + ie. "mpc5200b-soc\0mpc52xx-soc" +#interrupt-cells int must be <3>. If it is not defined + here then it must be defined in every + soc device node. +bus-frequency int IPB bus frequency in HZ. Clock rate + used by most of the soc devices. + Defining it here avoids needing it + added to every device node. + +4) soc5200 child nodes +---------------------- +Any on chip SOC devices available to Linux must appear as soc5200 child nodes. + +Note: in the tables below, '*' matches all <chip> values. ie. +*-pic would translate to "mpc5200-pic\0mpc52xx-pic" + +Required soc5200 child nodes: +name device_type compatible Description +---- ----------- ---------- ----------- +cdm@<addr> cdm *-cmd Clock Distribution +pic@<addr> interrupt-controller *-pic need an interrupt + controller to boot +bestcomm@<addr> dma-controller *-bestcomm 52xx pic also requires + the bestcomm device + +Recommended soc5200 child nodes; populate as needed for your board +name device_type compatible Description +---- ----------- ---------- ----------- +gpt@<addr> gpt *-gpt General purpose timers +rtc@<addr> rtc *-rtc Real time clock +mscan@<addr> mscan *-mscan CAN bus controller +pci@<addr> pci *-pci PCI bridge +serial@<addr> serial *-psc-uart PSC in serial mode +i2s@<addr> i2s *-psc-i2s PSC in i2s mode +ac97@<addr> ac97 *-psc-ac97 PSC in ac97 mode +spi@<addr> spi *-psc-spi PSC in spi mode +irda@<addr> irda *-psc-irda PSC in IrDA mode +spi@<addr> spi *-spi MPC52xx spi device +ethernet@<addr> network *-fec MPC52xx ethernet device +ata@<addr> ata *-ata IDE ATA interface +i2c@<addr> i2c *-i2c I2C controller +usb@<addr> usb-ohci-be *-ohci,ohci-be USB controller +xlb@<addr> xlb *-xlb XLB arbritrator + +IV - Extra Notes +================ + +1. Interrupt mapping +-------------------- +The mpc52xx pic driver splits hardware IRQ numbers into two levels. The +split reflects the layout of the PIC hardware itself, which groups +interrupts into one of three groups; CRIT, MAIN or PERP. Also, the +Bestcomm dma engine has it's own set of interrupt sources which are +cascaded off of peripheral interrupt 0, which the driver interprets as a +fourth group, SDMA. + +The interrupts property for device nodes using the mpc52xx pic consists +of three cells; <L1 L2 level> + + L1 := [CRIT=0, MAIN=1, PERP=2, SDMA=3] + L2 := interrupt number; directly mapped from the value in the + "ICTL PerStat, MainStat, CritStat Encoded Register" + level := [LEVEL_HIGH=0, EDGE_RISING=1, EDGE_FALLING=2, LEVEL_LOW=3] diff --git a/Documentation/s390/CommonIO b/Documentation/s390/CommonIO index d684a6ac69a8..22f82f21bc60 100644 --- a/Documentation/s390/CommonIO +++ b/Documentation/s390/CommonIO @@ -74,7 +74,7 @@ Command line parameters Note: While already known devices can be added to the list of devices to be ignored, there will be no effect on then. However, if such a device - disappears and then reappeares, it will then be ignored. + disappears and then reappears, it will then be ignored. For example, "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore" @@ -82,7 +82,7 @@ Command line parameters devices. The devices can be specified either by bus id (0.0.abcd) or, for 2.4 backward - compatibilty, by the device number in hexadecimal (0xabcd or abcd). + compatibility, by the device number in hexadecimal (0xabcd or abcd). * /proc/s390dbf/cio_*/ (S/390 debug feature) diff --git a/Documentation/s390/Debugging390.txt b/Documentation/s390/Debugging390.txt index 4dd25ee549e9..3f9ddbc23b27 100644 --- a/Documentation/s390/Debugging390.txt +++ b/Documentation/s390/Debugging390.txt @@ -7,7 +7,7 @@ Overview of Document: ===================== -This document is intended to give an good overview of how to debug +This document is intended to give a good overview of how to debug Linux for s/390 & z/Architecture. It isn't intended as a complete reference & not a tutorial on the fundamentals of C & assembly. It doesn't go into 390 IO in any detail. It is intended to complement the documents in the @@ -300,7 +300,7 @@ On z/Architecture our page indexes are now 2k in size but only mess with 2 segment indices each time we mess with a PMD. -3) As z/Architecture supports upto a massive 5-level page table lookup we +3) As z/Architecture supports up to a massive 5-level page table lookup we can only use 3 currently on Linux ( as this is all the generic kernel currently supports ) however this may change in future this allows us to access ( according to my sums ) @@ -502,7 +502,7 @@ Notes: ------ 1) The only requirement is that registers which are used by the callee are saved, e.g. the compiler is perfectly -capible of using r11 for purposes other than a frame a +capable of using r11 for purposes other than a frame a frame pointer if a frame pointer is not needed. 2) In functions with variable arguments e.g. printf the calling procedure is identical to one without variable arguments & the same number of @@ -846,7 +846,7 @@ of time searching for debugging info. The following self explanatory line should instead if the code isn't compiled -g, as it is much faster: objdump --disassemble-all --syms vmlinux > vmlinux.lst -As hard drive space is valuble most of us use the following approach. +As hard drive space is valuable most of us use the following approach. 1) Look at the emitted psw on the console to find the crash address in the kernel. 2) Look at the file System.map ( in the linux directory ) produced when building the kernel to find the closest address less than the current PSW to find the @@ -902,7 +902,7 @@ A. It is a tool for intercepting calls to the kernel & logging them to a file & on the screen. Q. What use is it ? -A. You can used it to find out what files a particular program opens. +A. You can use it to find out what files a particular program opens. @@ -911,7 +911,7 @@ Example 1 If you wanted to know does ping work but didn't have the source strace ping -c 1 127.0.0.1 & then look at the man pages for each of the syscalls below, -( In fact this is sometimes easier than looking at some spagetti +( In fact this is sometimes easier than looking at some spaghetti source which conditionally compiles for several architectures ). Not everything that it throws out needs to make sense immediately. @@ -1037,7 +1037,7 @@ e.g. man strace, man alarm, man socket. Performance Debugging ===================== -gcc is capible of compiling in profiling code just add the -p option +gcc is capable of compiling in profiling code just add the -p option to the CFLAGS, this obviously affects program size & performance. This can be used by the gprof gnu profiling tool or the gcov the gnu code coverage tool ( code coverage is a means of testing @@ -1419,7 +1419,7 @@ On a SMP guest issue a command to all CPUs try prefixing the command with cpu al To issue a command to a particular cpu try cpu <cpu number> e.g. CPU 01 TR I R 2000.3000 If you are running on a guest with several cpus & you have a IO related problem -& cannot follow the flow of code but you know it isnt smp related. +& cannot follow the flow of code but you know it isn't smp related. from the bash prompt issue shutdown -h now or halt. do a Q CPUS to find out how many cpus you have @@ -1602,7 +1602,7 @@ V000FFFD0 00010400 80010802 8001085A 000FFFA0 our 3rd return address is 8001085A as the 04B52002 looks suspiciously like rubbish it is fair to assume that the kernel entry routines -for the sake of optimisation dont set up a backchain. +for the sake of optimisation don't set up a backchain. now look at System.map to see if the addresses make any sense. @@ -1638,11 +1638,11 @@ more useful information. Unlike other bus architectures modern 390 systems do their IO using mostly fibre optics & devices such as tapes & disks can be shared between several mainframes, -also S390 can support upto 65536 devices while a high end PC based system might be choking +also S390 can support up to 65536 devices while a high end PC based system might be choking with around 64. Here is some of the common IO terminology Subchannel: -This is the logical number most IO commands use to talk to an IO device there can be upto +This is the logical number most IO commands use to talk to an IO device there can be up to 0x10000 (65536) of these in a configuration typically there is a few hundred. Under VM for simplicity they are allocated contiguously, however on the native hardware they are not they typically stay consistent between boots provided no new hardware is inserted or removed. @@ -1651,7 +1651,7 @@ HALT SUBCHANNEL,MODIFY SUBCHANNEL,RESUME SUBCHANNEL,START SUBCHANNEL,STORE SUBCH TEST SUBCHANNEL ) we use this as the ID of the device we wish to talk to, the most important of these instructions are START SUBCHANNEL ( to start IO ), TEST SUBCHANNEL ( to check whether the IO completed successfully ), & HALT SUBCHANNEL ( to kill IO ), a subchannel -can have up to 8 channel paths to a device this offers redunancy if one is not available. +can have up to 8 channel paths to a device this offers redundancy if one is not available. Device Number: @@ -1659,7 +1659,7 @@ This number remains static & Is closely tied to the hardware, there are 65536 of also they are made up of a CHPID ( Channel Path ID, the most significant 8 bits ) & another lsb 8 bits. These remain static even if more devices are inserted or removed from the hardware, there is a 1 to 1 mapping between Subchannels & Device Numbers provided -devices arent inserted or removed. +devices aren't inserted or removed. Channel Control Words: CCWS are linked lists of instructions initially pointed to by an operation request block (ORB), @@ -1674,7 +1674,7 @@ concurrently, you check how the IO went on by issuing a TEST SUBCHANNEL at each from which you receive an Interruption response block (IRB). If you get channel & device end status in the IRB without channel checks etc. your IO probably went okay. If you didn't you probably need a doctor to examine the IRB & extended status word etc. -If an error occurs, more sophistocated control units have a facitity known as +If an error occurs, more sophisticated control units have a facility known as concurrent sense this means that if an error occurs Extended sense information will be presented in the Extended status word in the IRB if not you have to issue a subsequent SENSE CCW command after the test subchannel. @@ -1749,7 +1749,7 @@ Interface (OEMI). This byte wide Parallel channel path/bus has parity & data on the "Bus" cable & control lines on the "Tag" cable. These can operate in byte multiplex mode for sharing between several slow devices or burst mode & monopolize the channel for the -whole burst. Upto 256 devices can be addressed on one of these cables. These cables are +whole burst. Up to 256 devices can be addressed on one of these cables. These cables are about one inch in diameter. The maximum unextended length supported by these cables is 125 Meters but this can be extended up to 2km with a fibre optic channel extended such as a 3044. The maximum burst speed supported is 4.5 megabytes per second however @@ -1759,7 +1759,7 @@ One of these paths can be daisy chained to up to 8 control units. ESCON if fibre optic it is also called FICON Was introduced by IBM in 1990. Has 2 fibre optic cables & uses either leds or lasers -for communication at a signaling rate of upto 200 megabits/sec. As 10bits are transferred +for communication at a signaling rate of up to 200 megabits/sec. As 10bits are transferred for every 8 bits info this drops to 160 megabits/sec & to 18.6 Megabytes/sec once control info & CRC are added. ESCON only operates in burst mode. @@ -1767,7 +1767,7 @@ ESCONs typical max cable length is 3km for the led version & 20km for the laser known as XDF ( extended distance facility ). This can be further extended by using an ESCON director which triples the above mentioned ranges. Unlike Bus & Tag as ESCON is serial it uses a packet switching architecture the standard Bus & Tag control protocol -is however present within the packets. Upto 256 devices can be attached to each control +is however present within the packets. Up to 256 devices can be attached to each control unit that uses one of these interfaces. Common 390 Devices include: @@ -2050,7 +2050,7 @@ list test.c:1,10 directory: Adds directories to be searched for source if gdb cannot find the source. -(note it is a bit sensititive about slashes) +(note it is a bit sensitive about slashes) e.g. To add the root of the filesystem to the searchpath do directory // @@ -2152,7 +2152,7 @@ program as if it just crashed on your system, it is usually called core & create current working directory. This is very useful in that a customer can mail a core dump to a technical support department & the technical support department can reconstruct what happened. -Provided the have an identical copy of this program with debugging symbols compiled in & +Provided they have an identical copy of this program with debugging symbols compiled in & the source base of this build is available. In short it is far more useful than something like a crash log could ever hope to be. diff --git a/Documentation/s390/cds.txt b/Documentation/s390/cds.txt index 32a96cc39215..05a2b4f7e38f 100644 --- a/Documentation/s390/cds.txt +++ b/Documentation/s390/cds.txt @@ -98,7 +98,7 @@ The following chapters describe the I/O related interface routines the Linux/390 common device support (CDS) provides to allow for device specific driver implementations on the IBM ESA/390 hardware platform. Those interfaces intend to provide the functionality required by every device driver -implementaion to allow to drive a specific hardware device on the ESA/390 +implementation to allow to drive a specific hardware device on the ESA/390 platform. Some of the interface routines are specific to Linux/390 and some of them can be found on other Linux platforms implementations too. Miscellaneous function prototypes, data declarations, and macro definitions @@ -114,7 +114,7 @@ the ESA/390 architecture has implemented a so called channel subsystem, that provides a unified view of the devices physically attached to the systems. Though the ESA/390 hardware platform knows about a huge variety of different peripheral attachments like disk devices (aka. DASDs), tapes, communication -controllers, etc. they can all by accessed by a well defined access method and +controllers, etc. they can all be accessed by a well defined access method and they are presenting I/O completion a unified way : I/O interruptions. Every single device is uniquely identified to the system by a so called subchannel, where the ESA/390 architecture allows for 64k devices be attached. @@ -338,7 +338,7 @@ DOIO_REPORT_ALL - report all interrupt conditions The ccw_device_start() function returns : 0 - successful completion or request successfully initiated --EBUSY - The device is currently processing a previous I/O request, or ther is +-EBUSY - The device is currently processing a previous I/O request, or there is a status pending at the device. -ENODEV - cdev is invalid, the device is not operational or the ccw_device is not online. @@ -361,7 +361,7 @@ first: -EIO: the common I/O layer terminated the request due to an error state If the concurrent sense flag in the extended status word in the irb is set, the -field irb->scsw.count describes the numer of device specific sense bytes +field irb->scsw.count describes the number of device specific sense bytes available in the extended control word irb->scsw.ecw[0]. No device sensing by the device driver itself is required. @@ -410,7 +410,7 @@ ccw_device_start() must be called disabled and with the ccw device lock held. The device driver is allowed to issue the next ccw_device_start() call from within its interrupt handler already. It is not required to schedule a -bottom-half, unless an non deterministically long running error recovery procedure +bottom-half, unless a non deterministically long running error recovery procedure or similar needs to be scheduled. During I/O processing the Linux/390 generic I/O device driver support has already obtained the IRQ lock, i.e. the handler must not try to obtain it again when calling ccw_device_start() or we end in a @@ -431,7 +431,7 @@ information prior to device-end the device driver urgently relies on. In this case all I/O interruptions are presented to the device driver until final status is recognized. -If a device is able to recover from asynchronosly presented I/O errors, it can +If a device is able to recover from asynchronously presented I/O errors, it can perform overlapping I/O using the DOIO_EARLY_NOTIFICATION flag. While some devices always report channel-end and device-end together, with a single interrupt, others present primary status (channel-end) when the channel is diff --git a/Documentation/s390/crypto/crypto-API.txt b/Documentation/s390/crypto/crypto-API.txt index 41a8b07da05a..71ae6ca9f2c2 100644 --- a/Documentation/s390/crypto/crypto-API.txt +++ b/Documentation/s390/crypto/crypto-API.txt @@ -17,8 +17,8 @@ arch/s390/crypto directory. 2. Probing for availability of MSA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ It should be possible to use Kernels with the z990 crypto implementations both -on machines with MSA available an on those without MSA (pre z990 or z990 -without MSA). Therefore a simple probing mechanisms has been implemented: +on machines with MSA available and on those without MSA (pre z990 or z990 +without MSA). Therefore a simple probing mechanism has been implemented: In the init function of each crypto module the availability of MSA and of the respective crypto algorithm in particular will be tested. If the algorithm is available the module will load and register its algorithm with the crypto API. @@ -26,7 +26,7 @@ available the module will load and register its algorithm with the crypto API. If the respective crypto algorithm is not available, the init function will return -ENOSYS. In that case a fallback to the standard software implementation of the crypto algorithm must be taken ( -> the standard crypto modules are -also build when compiling the kernel). +also built when compiling the kernel). 3. Ensuring z990 crypto module preference diff --git a/Documentation/s390/s390dbf.txt b/Documentation/s390/s390dbf.txt index 000230cd26db..0eb7c58916de 100644 --- a/Documentation/s390/s390dbf.txt +++ b/Documentation/s390/s390dbf.txt @@ -36,7 +36,7 @@ switches to the next debug area. This is done in order to be sure that the records which describe the origin of the exception are not overwritten when a wrap around for the current area occurs. -The debug areas itselve are also ordered in form of a ring buffer. +The debug areas themselves are also ordered in form of a ring buffer. When an exception is thrown in the last debug area, the following debug entries are then written again in the very first area. @@ -55,7 +55,7 @@ The debug logs can be inspected in a live system through entries in the debugfs-filesystem. Under the toplevel directory "s390dbf" there is a directory for each registered component, which is named like the corresponding component. The debugfs normally should be mounted to -/sys/kernel/debug therefore the debug feature can be accessed unter +/sys/kernel/debug therefore the debug feature can be accessed under /sys/kernel/debug/s390dbf. The content of the directories are files which represent different views @@ -87,11 +87,11 @@ There are currently 2 possible triggers, which stop the debug feature globally. The first possibility is to use the "debug_active" sysctl. If set to 1 the debug feature is running. If "debug_active" is set to 0 the debug feature is turned off. -The second trigger which stops the debug feature is an kernel oops. +The second trigger which stops the debug feature is a kernel oops. That prevents the debug feature from overwriting debug information that happened before the oops. After an oops you can reactivate the debug feature by piping 1 to /proc/sys/s390dbf/debug_active. Nevertheless, its not -suggested to use an oopsed kernel in an production environment. +suggested to use an oopsed kernel in a production environment. If you want to disallow the deactivation of the debug feature, you can use the "debug_stoppable" sysctl. If you set "debug_stoppable" to 0 the debug feature cannot be stopped. If the debug feature is already stopped, it |