On Mon 2020-08-10 23:36:20, John Ogness wrote:
[Added CC: Sergey and Steven]
I do not know which direction we want to take here. In this email I
state my stance.
On 2020-08-05, Petr Mladek <pmladek(a)suse.com> wrote:
> On Mon 2020-07-27 14:00:00, John Ogness wrote:
>> The .bss section for the h8300 is relatively small. A default
>> CONFIG_LOG_BUF_SHIFT value of 20 will create a static printk
>> ringbuffer that is too large. This is a problem with the new printk
>> ringbuffer because it now occupies double the .bss space.
>> Is it enough to ignore this problem and require h8300 users to use a
>> smaller CONFIG_LOG_BUF_SHIFT value (which they probably are anyway)?
>> Or should we change the default for CONFIG_H8300? I am open for
> In theory, it should be safe to lower the default value by one on all
> architectures. The dictionary and metadata are stored separately
> so more messages can be stored into the data ring.
I assume adjusting config defaults is a serious issue since it
implicitly affects all defconfigs.
Honestly, I do not have much experience with changing these defaults.
I could imagine that people hacking small devices might complain.
But I think that most people would not mind. And the default is
too small from my POV.
Accidentally, there is an independent proposal to increase the
It is motivated by lost messages, see
I think that the solution with two defaults for BASE_FULL and BASE_SMALL.
If it was my decision, I would choose to have CONFIG_LOG_BUF_SHIFT
represent the _combined_ size of text and dict buffers. I expect with
this interpretation, most systems will wrap similar to when they are
Hmm, I am not sure. It might help people that care about the used memory.
Well, it will still not cover the non-trivial size of the desc ring.
IMHO, most people are not aware of the dictionary. They are more
interested how many messages might get stored into the ring buffer.
For them, the current solution is good. Because the config option
describes the size of the pure text (ignoring id) that might be
We might just better describe the meaning in the config description.
At some point we could consider *replacing* CONFIG_LOG_BUF_SHIFT
CONFIG_LOG_TEXT_BUF_SHIFT and CONFIG_LOG_DICT_BUF_SHIFT config
options. But I don't see an immediate need for new replacement options.
I guess that we will end with this. Maybe we will even need to add
CONFIG_LOG_DESC_BUF_SHIFT. But let's keep the single option for now
until people complains.