Re: [PATCH v11 3/5] x86/earlyprintk: Allocate early log_buf as early as possible

Alexander Kuleshov
2015-06-10T09:26:06Z

2015-06-10 15:04 GMT+06:00 Borislav Petkov <bp@suse.de>:
> Yes, so this whole approach and what you're trying to achieve
> seems kinda confusing and wrong. First of all, the early_printk()
> machinery prints to a special console driver, i.e., I'm looking at the
> registration fun in setup_early_printk().
>
> So using early_printk() to print to dmesg is the wrong tool for the
> job. Actually, if you want to do that, you can just as well use plain
> printk() and try to make it work much earlier. Which is basically what
> you did by using the printk_func per_cpu ptr, but that was hacky and
> ugly.
>
> In order to do that right, you need to slow down first, think hard
> and look hard and long at printk(), log_buf, the statically allocated
> smaller __log_buf and the whole machinery behind it. Whether it can be
> used that early or not. And to explain why it can or why it cannot in
> your commit messages. Then test your stuff a *lot* on the hw you have
> access to because printk() is not a joke. It needs to be very reliable
> and to work.
>

That's right, I thought this too. But when you answered on 10th
(https://lkml.org/lkml/2015/6/8/157) revision that you do not see
earlyprintk messages in the dmesg output and I thought that he
should be there, but didint research printk/log_buf and related
stuff properly.

I will try to learn all earlyprintk related things in more clear way and
resend the patch.

Thank you.