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From: Graeme Russ on 28 Apr 2010 10:10
Hi All,

I've been working for a while now getting the x86 U-Boot port up to speed
to boot a linux kernel

I now have a root fs (build from Linux-From-Scratch and trimmed to <15M
using qemu) but all attempts to get any serial console output past
launching of init have failed.

I have taken the root fs which successfully boots using qemu and created a
jffs2 image and flashed it onto one of the on-board flash chips. U-Boot can
successfully 'ls' the root fs

My bootags are:

root=/dev/mtdblock1 rw rootfstype=jffs2 console=ttyS0,115200

as Linux can mount the root partition:
[ 1.447819] Serial: 8250/16550 driver, 6 ports, IRQ sharing disabled
[ 1.450027] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 1.452421] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[ 1.505824] brd: module loaded
[ 1.507350] Uniform Multi-Platform E-IDE driver
[ 1.509245] ide-gd driver 1.18
[ 1.512852] Serck eNET flash device: 0x1000000 at 0x10000000
[ 1.523853] eNET_Flash_0: Found 1 x16 devices at 0x0 in 16-bit bank
[ 1.524828] Intel/Sharp Extended Query Table at 0x0031
[ 1.526492] Intel/Sharp Extended Query Table at 0x0031
[ 1.527492] Using buffer write method
[ 1.528242] cfi_cmdset_0001: Erase suspend on write enabled
[ 1.529242] Serck eNET flash device: 0x1000000 at 0x11000000
[ 1.539872] eNET_Flash_1: Found 1 x16 devices at 0x0 in 16-bit bank
[ 1.540951] Intel/Sharp Extended Query Table at 0x0031
[ 1.543632] Intel/Sharp Extended Query Table at 0x0031
[ 1.544426] Using buffer write method
[ 1.545495] cfi_cmdset_0001: Erase suspend on write enabled
[ 1.547452] Serck eNET flash device: 0x80000 at 0x38000000
[ 1.549664] Found: AMD AM29LV040B
[ 1.550136] eNET_Boot_Flash: Found 1 x8 devices at 0x0 in 8-bit bank
[ 1.551136] number of JEDEC chips: 1
[ 1.551975] Adding Device 0
[ 1.556819] Partitioning Device 1
[ 1.558150] Creating 1 MTD partitions on "eNET_Flash_1":
[ 1.559150] 0x000000000000-0x000001000000 : "rootfs"
[ 1.563816] Adding Device 2
[ 1.568821] 8139too Fast Ethernet driver 0.9.28
[ 1.573803] eth0: RealTek RTL8139 at 0xc8896000, 00:40:f4:6e:67:ac, IRQ 10
[ 1.578796] eth1: RealTek RTL8139 at 0xc889a100, 00:40:f4:6e:67:ac, IRQ 9
[ 1.582822] TCP cubic registered
[ 1.584516] Using IPI Shortcut mode
[ 1.901864] VFS: Mounted root (jffs2 filesystem) on device 31:1.
[ 1.902926] Freeing unused kernel memory: 204k freed
[ 1.909817] Write protecting the kernel text: 1924k
[ 1.911896] Write protecting the kernel read-only data: 596k
[ 1.915842] kernel_execve(/sbin/init)

(I've added a printk in kernel_execve() which gives me the last line)

I initially had hot-plug support compiled into the kernel and was getting
a lot of kernel_execve(/sbin/hotplug) messages as well (plus a udev:
starting version 151 message which appear 100+ seconds and the above
messages), but I have since removed that and used mknod to create
/dev/ttyS0 directly

I have also tried the following test script:

#!/bin/bash
stty -F /dev/ttyS0 115200
cat hello > /dev/ttyS0

but still no luck

Does anyone have any advise on how I can debug this problem?

Regards,

Graeme
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Prev: [PATCH 2/4] blkdev: allow async blkdev_issue_flush requests
Next: cocbalt_lcdfb: correct sections