Messages in this thread |  | | | Date | Sat, 10 Jul 2010 14:27:52 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: [PATCH v2] x86: Early-boot serial I/O support |
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On 07/10/2010 02:17 PM, Pekka Enberg wrote: > Hi! > > On Sat, Jul 10, 2010 at 11:49 PM, Yinghai Lu <yinghai@kernel.org> wrote: >> can you analyze "console=uart8250,io,0x3f8,115200n8" instead? >> >> that is equal to "earlyprintk=ttyS0,115200 console=ttyS0,115200" >> >> so we only use one for all. >> >> also like to kill earlyprintk=ttyS0,115200 to favor earlycon > > hpa, what's your take on this? > > The 'console' variant seems overly complicated to me. We can add it > but we also need to check for 'earlyprintk' as long as it's supported > by the kernel. >
earlyprintk= seems to be preferred over console= these days. Quite frankly it's idiotic to have the user enter as many low-level details as one has to do for the console= one.
Now, as for the I/O base, the I/O base for legacy serial ports are available from a 4-element u16 array starting at absolute address 0x400. I don't think Linux currently examines that array -- instead relying on the hard-coded values 0x3f8, 0x2f8, 0x3e8, 0x2e8 -- but it might something to consider for the future. However, we should match the serial port subsystem there, of course.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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