This is not a kernel issue. I would suggest "won't fix" for this issue
from technical point of view:
1) This is not a bug but a feature restriction of the tool getconf[1]. We could
only retrieve the cpu cache information in another way, which is not what
getconf is using now. Because the upstream does not update the retrieve method,
we could not avoid to re-implement the retrieve method. Besides, 0 in this case
is expected because it means "no information available".[2]
2) This is not a kernel issue because kernel still provides the corresponding
cpu information.
lscpu could get the expected information because lscpu retrives the
cache information in another way. lspcu gets the information via Linux
virtual filesystem, including /proc/cpuinfo and /sys/devices/system/cpu,
and these virtual devices/files provided by Linux kernel show the
corresponding kernel is working and working well.
I would suggest to use lscpu in your case to retrieve L2/L3 cache
information instead of getconf.
[1] According to the source code where getconf retrieves cpu cache information
sysdeps/unix/sysv/linux/aarch64/sysconf.c:__sysconf
/* Unfortunately, the registers that contain the actual cache info
(CCSIDR_EL1, CLIDR_EL1, and CSSELR_EL1) are protected by the Linux
kernel (though they need not have been). However, CTR_EL0 contains
the *minimum* linesize in the entire cache hierarchy, and is
accessible to userland, for use in __aarch64_sync_cache_range,
and it is a reasonable assumption that the L1 cache will have that
minimum line size. */
[2] Please refer to the comments in this source file
./sysdeps/posix/sysconf.c:__sysconf
case _SC_LEVEL1_ICACHE_SIZE:
case _SC_LEVEL1_ICACHE_ASSOC:
case _SC_LEVEL1_ICACHE_LINESIZE:
case _SC_LEVEL1_DCACHE_SIZE:
case _SC_LEVEL1_DCACHE_ASSOC:
case _SC_LEVEL1_DCACHE_LINESIZE:
case _SC_LEVEL2_CACHE_SIZE:
case _SC_LEVEL2_CACHE_ASSOC:
case _SC_LEVEL2_CACHE_LINESIZE:
case _SC_LEVEL3_CACHE_SIZE:
case _SC_LEVEL3_CACHE_ASSOC:
case _SC_LEVEL3_CACHE_LINESIZE:
case _SC_LEVEL4_CACHE_SIZE:
case _SC_LEVEL4_CACHE_ASSOC:
case _SC_LEVEL4_CACHE_LINESIZE:
/* In general we cannot determine these values. Therefore we
return zero which indicates that no information is
available. */
return 0;
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https://bugs.launchpad.net/bugs/1868028
Title:
L2\L3 cache display error for using "getconf -a" command"
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