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| \chapter{Running HelenOS} |
| |
| HelenOS .. |
| \section{Kernel Start} |
| When the HelenOS kernel starts up, it configures its output device |
| and starts booting. During the boot process it writes out some some |
| lines regarding memory size and available CPUs. The userspace |
| drivers and tasks take over the console as soon as the start-up activity |
| and developer kernel tests are finished. |
| |
| The console driver provides 12 virtual consoles, 11 reserved |
| for applications, console 12 is reserved for kernel console. Pressing |
| function keys F1-F12 switches between the consoles. |
| |
| \section{KConsole} |
| KConsole is a kernel thread operating completely in priviledged mode. |
| It allows user to interact directly with kernel and even start directly |
| functions inside the kernel. |
| |
| The KConsole is shown by switching to console number 12. On some platforms |
| the kconsole screen is not restored to its previous contents. Press |
| enter to see a KConsole prompt. The function keys for switching terminals |
| do not work in KConsole, if you want to switch back to other console, use |
| the {\em continue} command. After executing the command, press a function key |
| to switch to other consoles. |
| |
| The basic editing facilities are very similar to {\em readline} conventions. |
| The left and right arrows, backspace and delete keys allow for convenient |
| editing of the text. The history of last ten commands can be retrieved |
| using up and down arrows. KConsole supports tab completion, double tab |
| shows a list of available commands. |
| |
| The first class of commands prints useful statistics from the running |
| operating systems. The commands are: |
| - zones - Prints a list of memory zones. |
| - zone <zone number> - Prints a detailed statistics about frame allocator. |
| - slabs - Prints a details statistics about slab allocator. |
| - scheduler - Prints scheduler queues on all cpus. |
| - threads - Prints list of existing threads, including information about |
| the thread state/ |
| - tasks - Prints list of tasks along with some basic IPC informations. |
| - ipc_tasks - Prints detailed information about IPC queues of a particular task. |
| - tlb - Prints contents of the Translation Lookaside Buffer on a processor (supported only on some platforms) |
| - exc - Prints table of registered exception handlers |
| |
| Kernel contains a searchable version of its symbol table. This is used |
| in error processing as well as for extending functionality of KConsole. |
| The following commands are supported: |
| - symaddr <address> - Finds an address in symbol table and prints appropriate |
| symbol name. |
| - call0, call1... <function> <args...> - Calls a C function function(args...). |
| Note that the tab-completion works for the function names. Because |
| of architecture calling convention, this command does not work correctly |
| on the ia64 platform. The arguments can be specified |
| - as a number or hexadecimal number: call1 task_kill 8 |
| - as a string: call1 printf "Hello world" |
| - as a hexadecimal number preceded by '*'. The argument is then read from |
| the given address: call2 printf "%X" *0x8000000 |
| - as a symbol name. In such case the value located in the memory |
| in the symbols address is used: call2 printf "%d" task_counter |
| - as a symbol name preceded by '&'. The address is used. |
| - as a symbol name preceded by '*'. In such a case the symbol is dereferenced. |
| - set4 <address|symbol name> - Saves 4-byte value on a given address. |
| |
| The mips, ia32 and amd64 platforms provide additional commands regarding |
| debugging facility - set and clear hardware breakpoints and watchpoints. |
| |
| \section{Emergency Functions} |
| It may happen that the IPC communication dies or that there are some |
| problems in the communication chain |
| {\em keboard driver} - {\em console} - {\em output driver}. |
| As long that at least the keyboard driver works, pressing Escape key three |
| times transfers control to the KConsole immediately. Screen is not updated, |
| the user should press Enter to see the kconsole prompt. |
| |
| If a kernel panic occurs, the error handling automatially switches control |
| to the KConsole and allows users to inspect the failed kernel online. |
| On the SMP system the other processors are halted immediately. The kernel |
| contains its symbol table, so you can probably read some useful information |
| about the exact place where the panic occured. |