On 27/11/2024 1:42 pm, Mike Leach wrote:
Add an example config table generator to test loading configuration tables.
Provides a table buffer writer function that can be re-used in other userspace programs.
Table write format matches that expected by the corresponding reader in the configfs driver code.
Generates tables and outputs in form of binary files.
Add a config table file reader and printer. Takes in config table files and prints the contents. Uses table reader source from kernel driver.
Signed-off-by: Mike Leach mike.leach@linaro.org
MAINTAINERS | 1 + .../coresight/coresight-config-table.h | 5 +
Hi Mike,
Isn't there some convention about maintaining a copy of kernel headers in the tools? Especially as you wouldn't rebuild the tools after updating the kernel headers so breakages might go unnoticed.
[...]
+/*
- sets of presets leaves strobing window constant while varying period to allow
- experimentation with mark / space ratios for various workloads
- */
+static u64 afdo_set_a_presets[AFDO_NR_PRESETS][AFDO_NR_PARAM_SUM] = {
- { 2000, 100 },
- { 2000, 1000 },
- { 2000, 5000 },
- { 2000, 10000 },
- { 4000, 100 },
The comment above here looks like its for example1, this one does vary the window size.
Probably only example2 is enough, I assumed they were different but example2 is basically the same as example1 with an extra preset list. We could comment that the second preset list is optional and delete example1. Saves people reading more and wondering what the difference is.
I tried to make an example that doesn't use an existing feature by reacreating afdo from scratch which I thought would be a good example. It's pasted at the end. I had to copy paste the ETMv4 macros and constants though, I couldn't include them in the userspace generator because of this error:
coresight-config.h:10:10: fatal error: linux/coresight.h: No such file or directory 10 | #include <linux/coresight.h>
I also got this error when loading it:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
cscfg_reset_feat (drivers/hwtracing/coresight/coresight-config.c:64 coresight-config.c:124) coresight cscfg_load_config_sets (drivers/hwtracing/coresight/coresight-syscfg.c:217 coresight-syscfg.c:262 coresight-syscfg.c:492 coresight-syscfg.c:610) coresight cscfg_dyn_load_cfg_table (drivers/hwtracing/coresight/coresight-syscfg-configfs.c:294) coresight cscfg_cfg_load_table_write (drivers/hwtracing/coresight/coresight-syscfg-configfs.c:799) coresight configfs_release_bin_file (fs/configfs/file.c:415) __fput (fs/file_table.c:432) __fput_sync (fs/file_table.c:517) __arm64_sys_close (fs/open.c:1568 fs/open.c:1550 fs/open.c:1550) invoke_syscall (arch/arm64/kernel/syscall.c:? arch/arm64/kernel/syscall.c:49) el0_svc_common (include/linux/thread_info.h:127 arch/arm64/kernel/syscall.c:140) do_el0_svc (arch/arm64/kernel/syscall.c:152)
So I'm wondering if we can do the same thing by setting values via individual files rather than one binary blob which would avoid some of these issues. From what I understand the feature params can already be set directly this way via /sys/kernel/config/cs-syscfg/features/strobing/params/period/value
We'd have to add a way to add new configs with a mkdir, then the same things can be configured without needing an additional tool. Links between features and configs can be done with symlinks which is also mentioned in the configfs docs.
Something like this would be a bit like the current version:
# ls /config/cs-syscfg configurations features
# mkdir /config/cs-syscfg/features/my_config # ls /config/cs-syscfg/features/my_config description matches regs_desc params
# mkdir /config/cs-syscfg/features/my_config/regs_desc/TRCRSCTLRn0 # ls /config/cs-syscfg/features/my_config/TRCRSCTLRn0 type offset val mask
But another way could be to enumerate all possible regs for each device. This would remove the need to have all the #defines in whatever tool is making the config (avoiding the #include issue from above):
# mkdir /config/cs-syscfg/features/my_config # ls /config/cs-syscfg/features/my_config/regs_desc
regs_desc is initially empty, but specify what device it's for to make all the properties appear (or the mkdir could be done in an etmv4 folder):
# echo "SRC_ETM4" > matches # ls /config/cs-syscfg/features/my_config/regs_desc TRCRSCTLRn0 TRCRSCTLRn1 TRCRSCTLRn2 ... etc ...
Now type and offset don't need to be set:
# ls /config/cs-syscfg/features/my_config/regs_desc/TRCRSCTLRn0 val mask save
Don't we already have the full list of parameters in etm4_cfg_map_reg_offset(), so we can expose this to users via configfs directly rather than needing any tooling. And doesn't any new device that's supported by the config mechanism need to know about all its parameters, so it wouldn't remove any flexibility?