linux-kernel - Re: [PATCH 3/4] printk: Add consoles to a virtual "console" bus

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Message-ID: <20190312205254.GB5982@Haydn>
Date:   Tue, 12 Mar 2019 20:52:57 +0000
From:   Calvin Owens <calvinowens@...com>
To:     Petr Mladek <pmladek@...e.com>
CC:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Corbet <corbet@....net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH 3/4] printk: Add consoles to a virtual "console" bus

On Friday 03/08 at 16:53 +0100, Petr Mladek wrote:
> On Fri 2019-03-01 16:48:19, Calvin Owens wrote:
> > This patch embeds a device struct in the console struct, and registers
> > them on a "console" bus so we can expose attributes in sysfs.
> > 
> > Early console structures must still be static, since they're required
> > before we're able to allocate memory. The least ugly way I can come up
> > with to handle this is an "is_static" flag in the structure which makes
> > the gets and puts NOPs, and is checked in ->release() to catch mistakes.
> 
> I wonder if it might get detected by is_kernel_inittext().

I don't think inittext() in particular would work, since these actually need
to exist forever if you pass "earlyprintk=[...],keep" so they aren't __init.

But I bet you're right that we could catch the static case without needing
the explicit flag, something like is_module_address() (but it would also need
to work for the built-in case). I'll see if I can get this to work.

Thanks,
Calvin
 
> Best Regards,
> Petr