Comment 0 for bug 1824864

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.

Please backport this to xenial and up.