APPLIED: [PATCH 0/2][focal/linux-azure] The console log of ARM64 Ubuntu 18.04 has duplicate output

[Tim Gardner]

On 5/31/22 13:33, Tim Gardner wrote:
> BugLink: https://bugs.launchpad.net/bugs/1976399
> 
> SRU Justification
> 
> [Impact]
> 
> There is duplicate output on the console . LSG team identify the root cause and suggested to apply two patches below.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ad8cd1db80cc33337bdbee63c453ef6d5132474b
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e369d8227fd211be36242fc44a9dc2209e246b9a
> 
> What we are hitting is exactly in the second commit's log. Ubuntu kernel also needs the following diff:
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index f07367100ece..dca15e27123a 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2203,7 +2203,7 @@ static int __init console_setup(char *str)
> * for exacly this purpose.
> */
> if (str[0] == 0 || strcmp(str, "null") == 0) {
> - __add_preferred_console("ttynull", 0, NULL, NULL);
> + __add_preferred_console("ttynull", 0, NULL, NULL, true);
> return 1;
> }
> 
> Linux kernel: 5.4.0-1078-azure
> Tested in Azure
> Host version: 22477.1101-1-0
> Image: Canonical 0002-com-ubuntu-server-arm-preview-bionic 18_04-lts 18.04.202205020
> 
>  From Azure Serial Console, we can see duplicate output.
> 
> Such as:
> 
> [ 3.109140] Platform Keyring initialized
> [ 3.109140] Platform Keyring initialized
> [ 3.117148] Key type asymmetric registered
> [ 3.117148] Key type asymmetric registered
> [ 3.122303] Asymmetric key parser 'x509' registered
> [ 3.122303] Asymmetric key parser 'x509' registered
> 
> [Test Plan]
> 
> Microsoft tested
> 
> [Where things could go wrong]
> 
> The kernel log could get corrupted.
> 
> [Other Info]
> 
> SF: #00338148
> 
Applied to focal/linux-azure:master-next. Thanks.

-rtg

-- 
-----------
Tim Gardner
Canonical, Inc