[kbuild-all] Re: [linux-next:master 6188/10009] h8300-linux-ld: section .softirqentry.text VMA overlaps section .bss VMA

On Mon 2020-07-27 14:00:00, John Ogness wrote: 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. Let's look at my test system using the original log buffer[*]: text: 30 kB metadata: 14 kB dict: 9 kB The text takes more than half of the space. But the difference is not too huge. So decreasing CONFIG_LOG_BUF_SHIFT by one might be acceptable. Also it might make sense to decrease the size of the dict ring by two. I mean to have size of text:dict rings as 2:1. Well, it would be nice to check the statistic on more systems. That said, I am fine also with reducing the default only on h8300. It should be enough to define it in in arch/h8300/Kconfig. I see that, for example, PGTABLE_LEVELS variable is redefined on some architectures. ===================== [*] Below is how I got the above numbers: $> pahole -y printk_log kernel/printk/printk.o struct printk_log { u64 ts_nsec; /* 0 8 */ u16 len; /* 8 2 */ u16 text_len; /* 10 2 */ u16 dict_len; /* 12 2 */ u8 facility; /* 14 1 */ u8 flags:5; /* 15: 3 1 */ u8 level:3; /* 15: 0 1 */ u32 caller_id; /* 16 4 */ /* size: 20, cachelines: 1, members: 8 */ /* last cacheline: 20 bytes */ }; $> dmesg | wc -l 701 $> echo $((701 * 20)) 14020 # => metadata: 14 kB $> cat /dev/kmsg >/tmp/dev_kmsg $> cat /tmp/dev_kmsg | grep caller= | cut -d: -f2- | sed -e "s/^.*caller=T1;//" | wc -c 30997 # => text: 30 kB $> cat /tmp/dev_kmsg | grep -v caller= | wc -c 9293 # => dict: 9 kB Best Regards, Petr