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Diffstat (limited to 'doc/openocd.texi')
| -rw-r--r-- | doc/openocd.texi | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi index 4d13f073..b6be87e1 100644 --- a/doc/openocd.texi +++ b/doc/openocd.texi @@ -873,6 +873,20 @@ handling issues like: @itemize @bullet +@item @b{ARM Semihosting}... +@cindex ARM semihosting +When linked with a special runtime library provided with many +toolchains@footnote{See chapter 8 "Semihosting" in +@uref{http://infocenter.arm.com/help/topic/com.arm.doc.dui0203i/DUI0203I_rvct_developer_guide.pdf, +ARM DUI 0203I}, the "RealView Compilation Tools Developer Guide". +The CodeSourcery EABI toolchain also includes a semihosting library.}, +your target code can use I/O facilities on the debug host. That library +provides a small set of system calls which are handled by OpenOCD. +It can let the debugger provide your system console and a file system, +helping with early debugging or providing a more capable environment +for sometimes-complex tasks like installing system firmware onto +NAND or SPI flash. + @item @b{ARM Wait-For-Interrupt}... Many ARM chips synchronize the JTAG clock using the core clock. Low power states which stop that core clock thus prevent JTAG access. @@ -5675,6 +5689,7 @@ speeds, like the 32kHz startup clock of an AT91RM9200. @end deffn @deffn Command {arm7_9 semihosting} [@option{enable}|@option{disable}] +@cindex ARM semihosting Display status of semihosting, after optionally changing that status. Semihosting allows for code executing on an ARM target to use the @@ -6049,8 +6064,12 @@ This finishes by listing the current vector catch configuration. @cindex tracing @cindex libdcc @cindex DCC -OpenOCD can process certain requests from target software. Currently -@command{target_request debugmsgs} +OpenOCD can process certain requests from target software, when +the target uses appropriate libraries. +The most powerful mechanism is semihosting, but there is also +a lighter weight mechanism using only the DCC channel. + +Currently @command{target_request debugmsgs} is supported only for @option{arm7_9} and @option{cortex_m3} cores. These messages are received as part of target polling, so you need to have @command{poll on} active to receive them. |