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GDB for RISC-V always uses target descriptions. When the target doesn't provide a target description then a default is selected. Usually this default is selected based on the properties of the executable being debugged. However, when there is no executable being debugged we currently fallback to the riscv:rv64 target description as the default. This leads to strange behaviour like this: $ gdb (gdb) set architecture riscv:rv32 (gdb) p sizeof ($pc) $1 = 8 Despite the users specifically setting the architecture to riscv:rv32 GDB still thinks that the target has riscv:rv64 register sizes. The above is a bit of a contrived situation. I actually ran into this situation while trying to connect to a running riscv:rv32 target without supplying an executable (the target didn't provide a target description). When I tried to set a register on the target I ran into errors because GDB was passing 8 bytes to the target rather than the expected 4. Even when I manually specified the architecture (as above) I couldn't convince GDB to only send 4 bytes. This patch fixes this issue. Now, when we selected a default target description we will make use of the user selected architecture to guide our choice. In the above example we now get: $ gdb (gdb) set architecture riscv:rv32 (gdb) p sizeof ($pc) $1 = 4 And my real world example of connecting to a remote without an executable works fine. I've used the fact that we can ask GDB about $pc even when no executable is loaded as the basis for a test to cover this situation. gdb/ChangeLog: * riscv-tdep.c (riscv_features_from_gdbarch_info): Rename to... (riscv_features_from_bfd): ...this. Change parameter type to 'bfd*', and update as required. (riscv_find_default_target_description): Update call to riscv_features_from_bfd. Select a default xlen based on info.bfd_arch_info. (riscv_gdbarch_init): Update call to riscv_features_from_bfd. gdb/testsuite/ChangeLog: * gdb.arch/riscv-default-tdesc.exp: New file.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.