lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 30 Apr 2020 19:46:29 +0300 From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> To: Alper Nebi Yasak <alpernebiyasak@...il.com> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jslaby@...e.com>, Petr Mladek <pmladek@...e.com>, Sergey Senozhatsky <sergey.senozhatsky@...il.com>, linux-serial@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, Arvind Sankar <nivedita@...m.mit.edu>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, "David S. Miller" <davem@...emloft.net>, Feng Tang <feng.tang@...el.com> Subject: Re: [RFC PATCH v2 1/3] printk: Add function to set console to preferred console's driver On Thu, Apr 30, 2020 at 07:14:35PM +0300, Alper Nebi Yasak wrote: > Currently, add_preferred_console sets a preferred console, but doesn't > actually change /dev/console to match it. That part is handled within > register_device, where a newly registered console driver will be set as > /dev/console if it matches the preferred console. > > However, if the relevant driver is already registered, the only way to > set it as /dev/console is by un-registering and re-registering it. An > example is the xenfb_make_preferred_console() function: > > console_lock(); > for_each_console(c) { > if (!strcmp(c->name, "tty") && c->index == 0) > break; > } > console_unlock(); > if (c) { > unregister_console(c); > c->flags |= CON_CONSDEV; > c->flags &= ~CON_PRINTBUFFER; /* don't print again */ > register_console(c); > } > > The code above was introduced in commit 9e124fe16ff2 ("xen: Enable > console tty by default in domU if it's not a dummy"). In short, it's aim > is to set VT as the preferred console only after a working framebuffer > is registered and thus VT is not the dummy device. > > This patch introduces an update_console_to_preferred function that > handles the necessary /dev/console change. With this change, the example > above can be replaced with: > > console_lock(); > add_preferred_console("tty", 0, NULL); > update_console_to_preferred(); > console_unlock(); > > More importantly, these two calls can be moved to vt.c in order to bump > its priority when a non-dummy backend for it is introduced, solving that > problem in general. Even w/o looking into the code I believe it breaks more platforms than fixes anything. It was not first time one tries to do something about preferred consoles and it appeared to break working configurations. I would wait for PRINTK maintainers to tell, but to me it sounds like papering over the real issue which you don't understand (yet). -- With Best Regards, Andy Shevchenko
Powered by blists - more mailing lists