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    SubjectRe: [PATCH]serial: make early_uart to use early_prarm instead of console_initcall
    On 5/20/07, Andrew Morton <akpm@linux-foundation.org> wrote:
    > I'll queue this up for some testing, but I'd be a bit reluctant to send it
    > into Linus due to my poor understanding of what it actually does. What
    > _is_ an early console, and how does it differ from a non-early one?
    >
    > Someone help, please.
    >
    > Coudl you please provide a patch against
    > Documentation/kernel-parameters.txt as well?
    >
    the story:
    Bjorn refer to andi's early_printk to create one early_uart. it took
    console=uart,io,0x3f8,9600n8
    or console=uart,mem,0xfxxx,115200n8.
    and it is called via console_init. --- it is not really early uart for
    platform other than ia64.
    ia64 call early_serial_console_init explicitly, so it is some early.
    but it needs to late_initcall to do console switch.

    Gerd's patch (console handover) was merged into mainline. it will
    switch from early_printk to normal console in register_console via
    CON_BOOT flags.. ===> only for x86

    I produced one patch to change early_uart calling from console_init to
    early_param. So to make early_uart to real early_uart for all other
    platform in addition to ia64.
    it will take
    earlycon=uart,io,0x3f8,9600n8 console=ttyS0,9600n8

    but Bjorn said that don't let the customer to key two times about
    console command line.
    Then come this patch. will take
    earlycon=uart,io,0x3f8,9600n8
    and it will switch to console ttyS0 automatically. ---- by calling
    add_preferred_console.

    Still need Bjorn to:
    1. remove early_serial_console_init call in ia64 setup_arch.
    2. verify mem io 8250 compatiable card.

    for 2, in x86 platform we need to use fix_to_virt and fix map to give
    it one fixed virtual address. == like Eric did for usb debug port
    console.

    I will send out another in email about updated early dbgp console with
    current tree.

    YH
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