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Diffstat (limited to 'erts/doc/src/driver_entry.xml')
| -rw-r--r-- | erts/doc/src/driver_entry.xml | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/erts/doc/src/driver_entry.xml b/erts/doc/src/driver_entry.xml index a2efdf3ebc..929c485c36 100644 --- a/erts/doc/src/driver_entry.xml +++ b/erts/doc/src/driver_entry.xml @@ -34,6 +34,29 @@ <lib>driver_entry</lib> <libsummary>The driver-entry structure used by erlang drivers.</libsummary> <description> + <marker id="WARNING"/> + <warning><p><em>Use this functionality with extreme care!</em></p> + <p>A driver callback is executed as a direct extension of the + native code of the VM. Execution is not made in a safe environment. + The VM can <em>not</em> provide the same services as provided when + executing Erlang code, such as preemptive scheduling or memory + protection. If the driver callback function doesn't behave well, + the whole VM will misbehave.</p> + <list> + <item><p>A driver callback that crash will crash the whole VM.</p></item> + <item><p>An erroneously implemented driver callback might cause + a VM internal state inconsistency which may cause a crash of the VM, + or miscellaneous misbehaviors of the VM at any point after the call + to the driver callback.</p></item> + <item><p>A driver callback that do + <seealso marker="erl_driver#lengthy_work">lengthy work</seealso> + before returning will degrade responsiveness of the VM, + and may cause miscellaneous strange behaviors. Such strange behaviors + include, but are not limited to, extreme memory usage, and bad load + balancing between schedulers. Strange behaviors that might occur due + to lengthy work may also vary between OTP releases.</p></item> + </list> + </warning> <p> As of erts version 5.9 (OTP release R15B) the driver interface has been changed with larger types for the callbacks |