ErrDisp

From 3dbrew
Revision as of 08:21, 4 February 2015 by Guiand (talk | contribs) (Added preliminary information about errinfo format)
Jump to: navigation, search

This system process handles displaying the error screens, such as "an error has occurred, the system needs shutdown". This can also display a register dump for exceptions, and info for fatal errors. (Normally the black-screen errors are displayed on retail, while the latter is displayed on development units.)

The register dump/fatal error info can also be written to nandrw/sys/native.log. On retail consoles, the system does not notify ErrDisp that any user-land exceptions occurred, ErrDisp is only notified for this on dev/debug units. Therefore, on retail consoles native.log only contains info from fatal errors. Starting with 5.0.0-11 ErrDisp no longer writes logs to native.log, except when the error-type is value 5 and when other checks with the errorinfo structure are successful (normally processes using this port never use error-type 5).

The bottom screen displays the error screen like "error has occurred", even with a development 3DS. The top screen can display the development error info, this is only displayed when UNITINFO bit0 is clear, for a development 3DS.

ErrDisp handles "returning" to Home Menu via NSS:RebootSystem, which triggers a hardware system reboot.

ErrDisp error port "err:f"

Command Header Description
0x00010800 ThrowFatalError(0x80-byte errorinfo)
0x00020042 (size, (size<<14) | 2, errorinfoptr) This is similar to cmd1, except with this the input buffer is copied to final output errorinfo+0x80 instead of +0x0, via the ARM11 kernel. Max size is 0x100. ErrDisp doesn't do anything in the cmd-handler for this command at all, besides checking the command header and buffer header.

errinfo

Note: the following data is still only partly reliable

Type Name Info
1 byte ? unknown
1 byte ? unknown
2 bytes The type of error info struct (??)
4 bytes The return code of the errored function (?? - Inconsistent)
4 bytes caller_ptr The contents of the LR register - where the error was called from
4 bytes process_id The ID/Handle of the running process