Most Linux terminal emulators use ASCII 0x7f (^?) for backspace, rather than 0x08 (^H) since ^H is used by some programs for other purposes, such as help menus. This results in backspace not working in most Linux environments, particularly in emulated environments such as QEMU where telnet or xterm may be used to connect to the emulated UART. While in some cases this can be configured in the terminal emulator, it must be done on every connection, as if permently configured this will break all other uses of the terminal.
This change causes both ASCII 0x08 and 0x7F to be treated as backspace. This provides a working backspace when tested with minicom, screen, telnet, and xterm under Linux. I also tested teraterm and hyperterm under Windows connecting via rs232, and saw no regressions. (The delete key doesn't work on hyperterm both before and after the change)
This change removes the ASCII encoding for delete, however this did not cause regressions on any tested terminal emulators as they do not use the ASCII encoding for the delete key.
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Roy Franz roy.franz@linaro.org --- MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c index 4a008c9..c92d3d4 100644 --- a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c +++ b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c @@ -1212,6 +1212,14 @@ UnicodeToEfiKey ( switch (TerminalDevice->InputState) { case INPUT_STATE_DEFAULT:
+ switch (UnicodeChar) { + case 0x7f: + UnicodeChar = CHAR_BACKSPACE; + break; + default : + break; + } + break;
case INPUT_STATE_ESC: