Re: [PATCH 1/1] x86: Add config option to setup early serial console

From: H. Peter Anvin
Date: Thu Jun 12 2008 - 19:00:04 EST


Mike Travis wrote:

We could. My current debugging is in x86_64_start_kernel() almost at
the start of the function (before the "Kernel alive" message). The
code is below. (cut and pasted so no tabs)

One benefit of a startup option instead of a config option is we rely
on the standard distribution for the kernel and unless they set this
option it won't do us much good.

(Maybe the failed attempts was trying to tell me something? ;-)


The easiest way to get to something extremely early is to parse it out already in the setup code and pass in a flag in struct boot_params. Otherwise, the kernel command line is present in memory and can be copied or parsed in an ad hoc manner. For i386 it is copied in place already in the assembly code -- for x86-64 it looks like we could trivially move copy_bootdata until just past clear_bss().

-hpa
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