interesting
/
riscv-openocd
mirror of https://github.com/riscv/riscv-openocd.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Document how vector registers are exposed to gdb. (#570) 

Change-Id: Ie7cdef3717e107a9df0b48316cfbc547dea9a7fd
Signed-off-by: Tim Newsome <tim@sifive.com>
This commit is contained in:
Tim Newsome 2021-01-25 11:27:23 -08:00 committed by GitHub
parent 4d0efe0fbb
commit 3070dbb6ab
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 37 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
doc/openocd.texi
View File

@ -9938,6 +9938,43 @@ A @emph{hart} is a hardware thread. A hart may share resources (eg. FPU) with
another hart, or may be a separate core. RISC-V treats those the same, and
OpenOCD exposes each hart as a separate core.
@subsection Vector Registers
For harts that implement the vector extension, OpenOCD provides access to the
relevant CSRs, as well as the vector registers (v0-v31). The size of each
vector register is dependent on the value of vlenb. RISC-V allows each vector
register to be divided into selected-width elements, and this division can be
changed at run-time. Because OpenOCD cannot update register definitions at
run-time, it exposes each vector register to gdb as a union of fields of
vectors so that users can easily access individual bytes, shorts, words,
longs, and quads inside each vector register. It is left to gdb or
higher-level debuggers to present this data in a more intuitive format.
In the XML register description, the vector registers (when vlenb=16) look as
follows:
@example
<feature name="org.gnu.gdb.riscv.vector">
<vector id="bytes" type="uint8" count="16"/>
<vector id="shorts" type="uint16" count="8"/>
<vector id="words" type="uint32" count="4"/>
<vector id="longs" type="uint64" count="2"/>
<vector id="quads" type="uint128" count="1"/>
<union id="riscv_vector">
<field name="b" type="bytes"/>
<field name="s" type="shorts"/>
<field name="w" type="words"/>
<field name="l" type="longs"/>
<field name="q" type="quads"/>
</union>
<reg name="v0" bitsize="128" regnum="4162" save-restore="no"
type="riscv_vector" group="vector"/>
...
<reg name="v31" bitsize="128" regnum="4193" save-restore="no"
type="riscv_vector" group="vector"/>
</feature>
@end example
@subsection RISC-V Debug Configuration Commands
@deffn Command {riscv dump_sample_buf} [base64]