Forwarding Bjørn's interesting comments to the bug report. ----- Forwarded message from Bjørn Mork <[EMAIL PROTECTED]> -----
To: [EMAIL PROTECTED] From: Bjørn Mork <[EMAIL PROTECTED]> Subject: Re: Please help solve #504721 Date: Sat, 29 Nov 2008 23:35:12 +0100 Organization: Dystrophy on Doggerel X-Mailing-List: <[EMAIL PROTECTED]> archive/latest/136459 X-CRM114-Status: Good ( pR: 53.0237 ) Jurij Smakov <[EMAIL PROTECTED]> writes: > > We have recently recognized that serial console detection in the > installer is not working as expected, which resulted in RC bug > http://bugs.debian.org/504721. The problem is that there is no reliable platform independent way to detect the preferred console. It would have been really helpful if register_console() could have printed it's conclusions, but it doesn't. The guesswork done by reopen-console is correct, given that nothing has ever called add_preferred_console(). This fails on sparc64, and presumably other platforms where the preferred console is configured by the boot prom. The failure on sparc64 is cause by the following chain of events: - of_console_init() in arch/sparc64/kernel/prom.c sets of_console_device based on openboot prom settings - a number of (Sun) serial drivers will call sunserial_console_match() in drivers/serial/suncore.c, which calls add_preferred_console() in kernel/printk.c if the device matches of_console_device - add_preferred_console() adds the device to the console_cmdline structure - register_console() in kernel/printk.c will set the preferred console based on the console_cmdline structure, which contains both the kernel cmdline console options and the additions made by add_preferred_console() This can probably be fixed on sparc64 by parsing the output from of_console_init(). It is supposed to print "OF stdout device is: %s\n". But the problem will also affect other platforms. Just grep for add_preferred_console() in the kernel source to find other possible failure cases. Note that things sometimes may work even if add_preferred_console() is called. E.g. if the preferred console is registered first by chance, or if it is listed on the kernel command line. Bjørn -- It's well known that depravity is pretty fun -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] ** CRM114 Whitelisted by: WHITELIST ** ----- End forwarded message ----- --
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