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Diffstat (limited to 'c/src/lib/libc/README')
| -rw-r--r-- | c/src/lib/libc/README | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/c/src/lib/libc/README b/c/src/lib/libc/README new file mode 100644 index 0000000000..ee7a90501e --- /dev/null +++ b/c/src/lib/libc/README @@ -0,0 +1,37 @@ +-- +-- $Id$ +-- + +Overview of newlib support (newlib is from CYGNUS) + Each task can have its own libc state including: + open stdio files + strtok + multi precision arithmetic state + etc. + + This is implemented by a reentrancy data structure for each task. + + When a task is "started" (in RTEMS sense) the reentrancy structure + is allocated. Its address is stored in notepad[NOTEPAD_LAST]. + + When task is switched to, the value of global variable _impure_ptr + is changed to the value of the new tasks reentrancy structure. + + When a task is deleted + atexit() processing (for that task) happens + task's stdio buffers are flushed + + When exit(3) is called + calling task's atexit processing done + global libc state atexit processing done + (this will include any atexit routines installed by drivers) + executive is shutdown + causes a context switch back to bsp land + + +NOTE: + libc extension are installed by bsp_libc_init() + iff we are using clock interrupts. + This hack is necessary to allow the tmtests to avoid + timing the extensions. + |