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Diffstat (limited to 'sys/fs/procfs/README')
| -rw-r--r-- | sys/fs/procfs/README | 113 |
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diff --git a/sys/fs/procfs/README b/sys/fs/procfs/README new file mode 100644 index 0000000..38811b3 --- /dev/null +++ b/sys/fs/procfs/README @@ -0,0 +1,113 @@ +saute procfs lyonnais + +procfs supports two levels of directory. the filesystem root +directory contains a representation of the system process table. +this consists of an entry for each active and zombie process, and +an additional entry "curproc" which always represents the process +making the lookup request. + +each of the sub-directories contains several files. these files +are used to control and interrogate processes. the files implemented +are: + + file - xxx. the exec'ed file. + + status - r/o. returns process status. + + ctl - w/o. sends a control message to the process. + for example: + echo hup > /proc/curproc/note + will send a SIGHUP to the shell. + whereas + echo attach > /proc/1293/ctl + would set up process 1293 for debugging. + see below for more details. + + mem - r/w. virtual memory image of the process. + parts of the address space are readable + only if they exist in the target process. + a more reasonable alternative might be + to return zero pages instead of an error. + comments? + + note - w/o. writing a string here sends the + equivalent note to the process. + [ not implemented. ] + + notepg - w/o. the same as note, but sends to all + members of the process group. + [ not implemented. ] + + regs - r/w. process register set. this can be read + or written any time even if the process + is not stopped. since the bsd kernel + is single-processor, this implementation + will get the "right" register values. + a multi-proc kernel would need to do some + synchronisation. + +this then looks like: + +% ls -li /proc +total 0 + 9 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 0 + 17 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 1 + 89 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 10 + 25 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 2 +2065 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 257 +2481 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 309 + 265 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 32 +3129 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 390 +3209 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 400 +3217 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 401 +3273 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 408 + 393 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 48 + 409 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 50 + 465 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 57 + 481 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 59 + 537 dr-xr-xr-x 2 root kmem 0 Sep 21 15:06 66 + 545 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 67 + 657 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 81 + 665 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 82 + 673 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 83 + 681 dr-xr-xr-x 2 root wheel 0 Sep 21 15:06 84 +3273 dr-xr-xr-x 2 jsp staff 0 Sep 21 15:06 curproc +% ls -li /proc/curproc +total 408 +3341 --w------- 1 jsp staff 0 Sep 21 15:06 ctl +1554 -r-xr-xr-x 1 bin bin 90112 Mar 29 04:52 file +3339 -rw------- 1 jsp staff 118784 Sep 21 15:06 mem +3343 --w------- 1 jsp staff 0 Sep 21 15:06 note +3344 --w------- 1 jsp staff 0 Sep 21 15:06 notepg +3340 -rw------- 1 jsp staff 0 Sep 21 15:06 regs +3342 -r--r--r-- 1 jsp staff 0 Sep 21 15:06 status +% df /proc/curproc /proc/curproc/file +Filesystem 512-blocks Used Avail Capacity Mounted on +proc 2 2 0 100% /proc +/dev/wd0a 16186 13548 1018 93% / +% cat /proc/curproc/status +cat 446 439 400 81 12,0 ctty 748620684 270000 0 0 0 20000 nochan 11 20 20 20 0 21 117 + + + +the basic sequence of commands written to "ctl" would be + + attach - this stops the target process and + arranges for the sending process + to become the debug control process + wait - wait for the target process to come to + a steady state ready for debugging. + step - single step, with no signal delivery. + run - continue running, with no signal delivery, + until next trap or breakpoint. + <signame> - deliver signal <signame> and continue running. + detach - continue execution of the target process + and remove it from control by the debug process + +in a normal debugging environment, where the target is fork/exec'd by +the debugger, the debugger should fork and the child should stop itself +(with a self-inflicted SIGSTOP). the parent should do a "wait" then an +"attach". as before, the child will hit a breakpoint on the first +instruction in any newly exec'd image. + +$Id: README,v 3.1 1993/12/15 09:40:17 jsp Exp $ |
