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Paul Mackerras
49a4d9f67a
This logs 256 bits of data per cycle to a ring buffer in BRAM. The data collected can be read out through 2 new SPRs or through the debug interface. The new SPRs are LOG_ADDR (724) and LOG_DATA (725). LOG_ADDR contains the buffer write pointer in the upper 32 bits (in units of entries, i.e. 32 bytes) and the read pointer in the lower 32 bits (in units of doublewords, i.e. 8 bytes). Reading LOG_DATA gives the doubleword from the buffer at the read pointer and increments the read pointer. Setting bit 31 of LOG_ADDR inhibits the trace log system from writing to the log buffer, so the contents are stable and can be read. There are two new debug addresses which function similarly to the LOG_ADDR and LOG_DATA SPRs. The log is frozen while either or both of the LOG_ADDR SPR bit 31 or the debug LOG_ADDR register bit 31 are set. The buffer defaults to 2048 entries, i.e. 64kB. The size is set by the LOG_LENGTH generic on the core_debug module. Software can determine the length of the buffer because the length is ORed into the buffer write pointer in the upper 32 bits of LOG_ADDR. Hence the length of the buffer can be calculated as 1 << (31 - clz(LOG_ADDR)). There is a program to format the log entries in a somewhat readable fashion in scripts/fmt_log/fmt_log.c. The log_entry struct in that file describes the layout of the bits in the log entries. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> |
5 years ago | |
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| README | ||
| mw_debug.c | 5 years ago | |
README
mw_debug is the microwatt debugger. It can talk to the simulator using a socket. On an Arty board it uses the FTDI device via liburjtag. ## Building on Fedora ``` dnf install urjtag-devel make ``` If you commonly use it against one target, create an alias as follows: ``` alias mw="$HOME/microwatt/scripts/mw_debug/mw_debug -b jtag" $ mw gpr 0 10 Connected to libftdi driver. Found device ID: 0x0362d093 r0: 0000000000001094 r1: 0000000000001ed0 r2: 000000000000a000 r3: 0000000000000003 r4: 000000000000000d r5: 00000000ffff2ca5 r6: 00000000ffff3eb8 r7: 0000000000000000 r8: 00000000ffff3c33 r9: 0000000000000003 Core: running NIA: 00000000000011d4 MSR: 8000000000000001 ``` ## Building on Debian Debian disables the library in the urjtag package. Instead, build against local urjtag: ``` sudo apt install libftdi-dev git clone https://git.code.sf.net/p/urjtag/git urjtag cd urjtag/urjtag ./autogen.sh make ``` And then uncomment the following line in Makefile to build against that copy ``` CFLAGS += -I urjtag/urjtag/include/ -L urjtag/urjtag/src/.libs/ ``` To run: ``` alias mw="LD_LIBRARY_PATH=$HOME/microwatt/scripts/mw_debug/urjtag/urjtag/src/.libs/ $HOME/microwatt/scripts/mw_debug/mw_debug -b jtag" $ mw Connected to libftdi driver. Found device ID: 0x0362d093 Core: running NIA: 00000000000011b8 MSR: 8000000000000001 ```