Messages in this thread | | | Date | Fri, 6 Jan 2023 12:11:08 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH printk v4 8/8] printk: adjust string limit macros |
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On Thu 2023-01-05 11:43:35, John Ogness wrote: > The various internal size limit macros have names and/or values that > do not fit well to their current usage. > > Rename the macros so that their purpose is clear and, if needed, > provide a more appropriate value. In general, the new macros and > values will lead to less memory usage. The new macros are... > > PRINTK_MESSAGE_MAX: > > This is the maximum size for a formatted message on a console, > devkmsg, or syslog. It does not matter which format the message has > (normal or extended). It replaces the use of CONSOLE_EXT_LOG_MAX for > console and devkmsg. It replaces the use of CONSOLE_LOG_MAX for > syslog. > > Historically, normal messages have been allowed to print up to 1kB, > whereas extended messages have been allowed to print up to 8kB. > However, the difference in lengths of these message types is not > significant and in multi-line records, normal messages are probably > larger. Also, because 1kB is only slightly above the allowed record > size, multi-line normal messages could be easily truncated during > formatting. > > This new macro should be significantly larger than the allowed > record size to allow sufficient space for extended or multi-line > prefix text. A value of 2kB should be plenty of space. For normal > messages this represents a doubling of the historically allowed > amount. For extended messages it reduces the excessive 8kB size, > thus reducing memory usage needed for message formatting. > > PRINTK_PREFIX_MAX: > > This is the maximum size allowed for a record prefix (used by > console and syslog). It replaces PREFIX_MAX. The value is left > unchanged. > > PRINTKRB_RECORD_MAX: > > This is the maximum size allowed to be reserved for a record in the > ringbuffer. It is used by all readers and writers with the printk > ringbuffer. It replaces LOG_LINE_MAX. > > Previously this was set to "1kB - PREFIX_MAX", which makes some > sense if 1kB is the limit for normal message output and prefixes are > enabled. However, with the allowance of larger output and the > existence of multi-line records, the value is rather bizarre. > > Round the value up to 1kB. > > Signed-off-by: John Ogness <john.ogness@linutronix.de>
I like this.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards, Petr
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