Messages in this thread | | | Date | Sun, 20 May 2007 21:29:20 -0700 | From | "Yinghai Lu" <> | Subject | Re: [PATCH]serial: make early_uart to use early_prarm instead of console_initcall |
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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.
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