[PATCH] powerpc: opal-msglog: Report size of memcons log

[PATCH] powerpc: opal-msglog: Report size of memcons log

[Joel Stanley]

The OPAL memory console is reported to be size zero, as we do not
initialise the struct attr with any size information due to the size
being variable. This leads users to think that the console is empty.

Instead report the maximum size.

Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 arch/powerpc/platforms/powernv/opal-msglog.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-msglog.c b/arch/powerpc/platforms/powernv/opal-msglog.c
index 39d6ff9e5630..8486b2ceb510 100644
--- a/arch/powerpc/platforms/powernv/opal-msglog.c
+++ b/arch/powerpc/platforms/powernv/opal-msglog.c
@@ -123,6 +123,10 @@ void __init opal_msglog_init(void)
 		return;
 	}
 
+	/* Report maximum size */
+	opal_msglog_attr.size =  be64_to_cpu(mc->ibuf_size) +
+		be64_to_cpu(mc->obuf_size);
+
 	opal_memcons = mc;
 }
 
-- 
2.11.0

Re: [PATCH] powerpc: opal-msglog: Report size of memcons log

[Michael Ellerman]

Joel Stanley <joel@jms.id.au> writes:

> The OPAL memory console is reported to be size zero, as we do not
> initialise the struct attr with any size information due to the size
> being variable. This leads users to think that the console is empty.

Hmm OK. That is a general property of /proc and /sys files that are
dynamically generated, so users probably need to get used to it :)

> Instead report the maximum size.

But OK. That sounds sane enough. My only worry is that it might confuse
some tools, ie. the file claims to be x bytes but is actually smaller.
But I guess that can actually happen anyway with any file.

So I'll merge this and stop blabbing :)

cheers

Re: [PATCH] powerpc: opal-msglog: Report size of memcons log

[Michael Ellerman]

Michael Ellerman <mpe@ellerman.id.au> writes:

> Joel Stanley <joel@jms.id.au> writes:
>
>> The OPAL memory console is reported to be size zero, as we do not
>> initialise the struct attr with any size information due to the size
>> being variable. This leads users to think that the console is empty.
>
> Hmm OK. That is a general property of /proc and /sys files that are
> dynamically generated, so users probably need to get used to it :)
>
>> Instead report the maximum size.
>
> But OK. That sounds sane enough. My only worry is that it might confuse
> some tools, ie. the file claims to be x bytes but is actually smaller.
> But I guess that can actually happen anyway with any file.
>
> So I'll merge this and stop blabbing :)

Hmm, but then I get:

  $ ls -la msglog 
  -r--r--r-- 1 root root 4503599627370496 Jan 25 13:09 msglog

I know firmware likes to spit out lots of messages, but 4PB seems a bit
large :P

I fixed it with the patch below which I'll fold in, resulting in:

  $ ls -la msglog 
  -r--r--r-- 1 root root 1048576 Jan 25 13:30 msglog


Which seems more likely.

cheers

diff --git a/arch/powerpc/platforms/powernv/opal-msglog.c b/arch/powerpc/platforms/powernv/opal-msglog.c
index 8486b2ceb510..7a9cde0cfbd1 100644
--- a/arch/powerpc/platforms/powernv/opal-msglog.c
+++ b/arch/powerpc/platforms/powernv/opal-msglog.c
@@ -124,8 +124,8 @@ void __init opal_msglog_init(void)
 	}
 
 	/* Report maximum size */
-	opal_msglog_attr.size =  be64_to_cpu(mc->ibuf_size) +
-		be64_to_cpu(mc->obuf_size);
+	opal_msglog_attr.size =  be32_to_cpu(mc->ibuf_size) +
+		be32_to_cpu(mc->obuf_size);
 
 	opal_memcons = mc;
 }

Re: [PATCH] powerpc: opal-msglog: Report size of memcons log

[Joel Stanley]

On Wed, Jan 25, 2017 at 1:33 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> Michael Ellerman <mpe@ellerman.id.au> writes:
>
>> Joel Stanley <joel@jms.id.au> writes:
>>
>>> The OPAL memory console is reported to be size zero, as we do not
>>> initialise the struct attr with any size information due to the size
>>> being variable. This leads users to think that the console is empty.
>>
>> Hmm OK. That is a general property of /proc and /sys files that are
>> dynamically generated, so users probably need to get used to it :)
>>
>>> Instead report the maximum size.
>>
>> But OK. That sounds sane enough. My only worry is that it might confuse
>> some tools, ie. the file claims to be x bytes but is actually smaller.
>> But I guess that can actually happen anyway with any file.
>>
>> So I'll merge this and stop blabbing :)
>
> Hmm, but then I get:
>
>   $ ls -la msglog
>   -r--r--r-- 1 root root 4503599627370496 Jan 25 13:09 msglog
>
> I know firmware likes to spit out lots of messages, but 4PB seems a bit
> large :P
>
> I fixed it with the patch below which I'll fold in, resulting in:
>
>   $ ls -la msglog
>   -r--r--r-- 1 root root 1048576 Jan 25 13:30 msglog
>
>
> Which seems more likely.

My bad. In my excitement I forgot to mention that this was just an
idea, and I had not boot tested it.

Thanks for testing it and finding the bug.

Cheers,

Joel

Re: powerpc: opal-msglog: Report size of memcons log

[Michael Ellerman]

On Fri, 2017-01-13 at 03:53:49 UTC, Joel Stanley wrote:
> The OPAL memory console is reported to be size zero, as we do not
> initialise the struct attr with any size information due to the size
> being variable. This leads users to think that the console is empty.
> 
> Instead report the maximum size.
> 
> Signed-off-by: Joel Stanley <joel@jms.id.au>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/14a41d6b7572026cf8fc88ee72e81b

cheers