Messages in this thread | | | Subject | Re: [PATCH v9 3/3] printk: fix double printing with earlycon | From | Aleksey Makarov <> | Date | Fri, 12 May 2017 00:13:57 +0300 |
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On 05/11/2017 11:41 AM, Sergey Senozhatsky wrote: > On (05/11/17 17:24), Sergey Senozhatsky wrote: >> On (05/09/17 10:29), Sabrina Dubroca wrote: >> [..] >>> That's caused a change of behavior in my qemu setup, with this cmdline >>> >>> root=/dev/sda1 console=ttyS1 console=ttyS0 >>> >>> Before, the kernel logs appeared on ttyS1, and I logged in with ttyS0 >>> (with my setup, ttyS1 is a file and ttyS0 is unix socket). Now, the >>> kernel logs go to ttyS0. I need to swap the two console= parameters to >>> restore behavior. >>> >>> There might be some other problem (in qemu?) though, because adding >>> console=tty0 anywhere on that cmdline makes the logs appear on both >>> tty0 and one ttyS* (but only one of them, and the ordering of the >>> ttyS* matters). >> >> thanks for the report. >> >> so we have ttyS1 first and ttyS0 last. >> after commit in question, register_console() iterates console_cmdline >> in reverse order so we see ttyS0 first, then we hit `if (newcon->index < 0)' >> condition, set newcon to ttyS0, because we iterate in reverse order now, and >> break out. so we enable ttyS0, instead of ttyS1. >> >> previously, we iterated console_cmdline from index 0 and saw ttyS1 first. >> so the same `if (newcon->index < 0)' condition would set newcone to ttyS1, >> and, thus, we would enable ttyS1, not ttyS0. > > Alexey, > can we have preferred console at offset 0 (not at console_cmdline_cnt - 1) > and restore the previous register_console() iteration order?
I don't quite understand what is the problem. Give me more time please. I hope I will be able to look at this on the weekend.
Thank you Aleksey Makarov
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