** Also affects: systemd (Ubuntu)
Importance: Undecided
Status: New
** Description changed:
CONFIG_LOG_BUF_SHIFT
policy<{
'amd64' : '18',
'arm64' : '14',
'armhf' : '17',
'i386' : '17',
'ppc64el': '17',
's390x' : '17'}>
Please set CONFIG_LOG_BUF_SHIFT to at least 17 on arm64.
Potentially bump all 64-bit arches to 18 (or higher!) as was done on
amd64, meaning set 18 on arm64 s390x ppc64el.
I have a systemd autopkgtest test that asserts that we see Linux kernel
command line in the dmesg (journalctl -k -b). And it is consistently
failing on arm64 scalingstack KVM EFI machines with messages of "missing
81 kernel messages".
config LOG_BUF_SHIFT
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
range 12 25
default 17
depends on PRINTK
help
Select the minimal kernel log buffer size as a power of 2.
The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
parameter, see below. Any higher size also might be forced
by "log_buf_len" boot parameter.
Examples:
17 => 128 KB
16 => 64 KB
15 => 32 KB
14 => 16 KB
13 => 8 KB
12 => 4 KB
14 sounds like redictiously low for arm64. given that 17 is default
across 32-bit arches, and 18 is default on amd64.
On a related note, we have CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT
policy<{'amd64': '13', 'arm64': '13', 'armhf': '13', 'i386': '13', 'ppc64el':
'13', 's390x': '13'}>
I'm not sure if we want to bump these up to LOG_BUF_SHIFT size or not.
+ Please backport this to xenial and up.
- Please backport this to xenial and up.
+
+
+ === systemd ===
+
+ systemd, boot-and-services test case can bump the ring buffer before
+ running the tests.
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https://bugs.launchpad.net/bugs/1824864
Title:
CONFIG_LOG_BUF_SHIFT set to 14 is too low on arm64
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