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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/xmon: Change printk() to pr_cont()
In-Reply-To: <c8a6ec704416ecd5ff2bd26213c9bc026bdd19de.1607077340.git.christophe.leroy@csgroup.eu>
References: <c8a6ec704416ecd5ff2bd26213c9bc026bdd19de.1607077340.git.christophe.leroy@csgroup.eu>
Date:   Fri, 04 Dec 2020 21:56:49 +1100
Message-ID: <87h7p1vnym.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Since some time now, printk() adds carriage return, leading to
> unusable xmon output:
>
> [   54.288722] sysrq: Entering xmon
> [   54.292209] Vector: 0  at [cace3d2c]
> [   54.292274]     pc:
> [   54.292331] c0023650

...

> diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c
> index 5c1a50912229..9b0d85bff021 100644
> --- a/arch/powerpc/xmon/nonstdio.c
> +++ b/arch/powerpc/xmon/nonstdio.c
> @@ -178,7 +178,7 @@ void xmon_printf(const char *format, ...)
>  
>  	if (n && rc == 0) {
>  		/* No udbg hooks, fallback to printk() - dangerous */
> -		printk("%s", xmon_outbuf);
> +		pr_cont("%s", xmon_outbuf);
>  	}

Ah OK, in the case where there's no udbg backend. We basically always
have a udbg backend on 64-bit, via hvc console. Which explains why we
haven't noticed it.

Will pick up the patch.

cheers