Hi Daniel,
good point. I'll try that.
For now, I have configured the Kernel for XIP. In the device tree file, I have
the bootargs as follows:
chosen {
bootargs = "earlyprintk console=/dev/ttyS0 keep_bootcon
root=/dev/ram0";
};
My self-made bootloader then copies the device tree blob into the SDRAM and
branches to the kernel entry point in the Flash memory. The kernel then prints
the following info on the terminal:
Booting Linux on physical CPU 0x0
Linux version 3.10.2 (tobias@zap) (gcc version 4.7.4 20130613 (release) [ARM/emb
edded-4_7-branch revision 200083] (GNU Tools for ARM Embedded Processors) ) #60
Sun Jul 28 16:55:32 CEST 2013
CPU: ARM7TDMI [41007700] revision 0 (ARMv3), cr=00000000
CPU: VIVT data cache, VIVT instruction cache
Machine: LPC24XX SoC (Flattened Device Tree), model: LPC2468 Board
bootconsole [earlycon0] enabled
debug: skip boot console de-registration.
DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map
init early
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 12192
Kernel command line: earlyprintk console=/dev/ttyS0 keep_bootcon root=/dev/ram0
PID hash table entries: 256 (order: -2, 1024 bytes)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Sorting __ex_table...
Memory: 48MB = 48MB total
Memory: 48424k/48424k available, 728k reserved, 0K highmem
Virtual kernel memory layout:
vector : 0xa0000000 - 0xa0001000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
vmalloc : 0x00000000 - 0xffffffff (4095 MB)
lowmem : 0xa0000000 - 0xa3000000 ( 48 MB)
.text : 0x80000000 - 0x8013c024 (1265 kB)
.init : 0xa000a000 - 0xa000e000 ( 16 kB)
.data : 0xa0008000 - 0xa001da00 ( 87 kB)
.bss : 0xa001da00 - 0xa00451a0 ( 158 kB)
sched_clock: 32 bits at 20 Hz, resolution 50000000ns, wraps every 4294967246ms
Console: colour dummy device 80x30
Calibrating delay loop... 5.78 BogoMIPS (lpj=28928)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 512
bio: create slab <bio-0> at 0
NetWinder Floating Point Emulator V0.97 (extended precision)
io scheduler noop registered (default)
Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
brd: module loaded
Warning: unable to open an initial console.
VFS: Cannot open root device "ram0" or unknown-block(1,0): error -14
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)
Here it looks like my kernel basically should work; the reason why it cannot
read the initramfs is somewhat strange. But I would definitely prefer to use
zImage because it saves Flash and download speed is therefore also faster :-)
OK, I'm going to check this LR thing.
Tobias
________________________________________
Von: uclinux-dev-boun...@uclinux.org [uclinux-dev-boun...@uclinux.org]" im
Auftrag von "Daniel Glöckner [daniel...@gmx.net]
Gesendet: Sonntag, 28. Juli 2013 14:38
An: uClinux development list
Betreff: Re: [uClinux-dev] ARM7TDMI zImage booting
Hi Tobias,
On Sun, Jul 28, 2013 at 12:22:54PM +0000, Plüss Tobias TA.E.1001 wrote:
> It seems difficult to find out what causes the crash. Because when I step
> through the code, many many instructions work without any problem;
> yesterdeay in the evening, I stepped about half an hour through the code,
> and *every* instruction was okay, but when I let the CPU run, it comes to
> the "critical point" after a short while, so it looks like the thing
> causing the crash is not near the beginning.
then what are the instructions around LR (aka R14) when it has entered
the exception handler?
Daniel
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