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So I have a machine that has 2 onboard serial ports and two pci serial cards that have two ports each, yet there's only 4 serial TTYs, TTYS[0123], created (0 and 1 for the internal 2 and 3 for the first card). The last card is recognized, is identical to the first, and is functional. I found reference online that the built in kernel serial module is usually compiled to support only 4 by default and that passing the parameter "nr_uarts=16" or some greater number should override that option, but does not appear to be working as there is still only 4 serial TTYs and I have not been able to find any other options and "modinfo serial", the module that it says its using, does not return and results. Does anyone have any ideas on how to overcome this? There doesn't seem to be any other documentation I can find other than the "nr_uarts" option.
Last edited by PreparationH67 (2013-06-28 16:57:52)
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Hi, the stock kernel is configured to host 32 (CONFIG_SERIAL_8250_NR_UARTS=32) 8250 UARTs, registering 4 of them at runtime (CONFIG_SERIAL_8250_RUNTIME_UARTS=4), The second parameter can be adjusted at kernel command line by passing 8250.nr_uarts=n, where 1 <= n <= CONFIG_SERIAL_8250_NR_UARTS
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Thanks, that worked. I did see a mention of that, but the documentation was a bit confusing and made it seem like the other option was the correct one with the way the module is compiled in. Guess I should have tried it anyway.
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