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Diffstat (limited to 'Documentation/s390/Debugging390.txt')
| -rw-r--r-- | Documentation/s390/Debugging390.txt | 38 |
1 files changed, 19 insertions, 19 deletions
diff --git a/Documentation/s390/Debugging390.txt b/Documentation/s390/Debugging390.txt index 4dd25ee549e..3f9ddbc23b2 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. |