It isn't going to be the exception handling mechanism.
FAQ: http://www.denx.de/twiki/bin/view/DULG/UBootCrashAfterRelocation
Note to Wolfgang: I added some more text to the above link. I was going to add a new section to the linux section of the FAQ to refer to the above link, but forgot how to add sections given your DULG structuring :-(. I propose the following be added:
%SECTION0{name=LinxRandomCrash}% Linux crashes randomly
Question:: On my board, linux crashes randomly or has random exceptions (especially floating point exceptions if it is a PowerPC processor). Why?
Answer:: Quite likely your SDRAM initialization is bad. See UBootCrashAfterRelocation for more information. <p></p> On a PowerPC, the instructions beginning with 0xFF are floating point instructions. When your memory subsystem fails, the PowerPC is reading bad values (0xFF) and thus executing illegal floating point instructions.
gvb
-----Original Message----- From: u-boot-users-admin@lists.sourceforge.net [mailto:u-boot-users-admin@lists.sourceforge.net]On Behalf Of haigao Sent: Friday, August 27, 2004 3:16 AM To: u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] Help--750FX,Cannot handle DEC or External Interrupt exception.U-Boot-1.1.1, ELDK3.0,RedHat
My target platform is with 750FX and MPC107, 256M ram, a
NS16c552 serial and also a Intel 82559 compatiable ethernet controller.
Which board configuration is this, and which version of U-Boot?
U-Boot 1.1.1 ELDK3.0 RedHat9.0,
I made our board's configuration file by copying and modifying the BAB7xx.h.
[And another question in anticipation of your reply (a
new board
configuration being ported by you based on an old version
of U-Boot):
are you absolutely sure that your SDRAM init code is correct?]
Yes, I am sure my SDRAM init code is correct, because I had Vxworks running on many pieces of boards for many days Also, I've coded a program to test SDRAM detailly, but on Vxworks.
I have tested my situation for already many times. And found:
- Sometimes, even program exception handling cannot work
when I use "go 0x8000(or 0x9000, or 0x123456, or any other place"(Of course I examined the data there). 2)Sometimes, even I set IP bit in MSR register, exception handling also cannot work. 3)My hundreds of trying seemed ruleless.
I guess, the cause maybe the cache or exception handling mechanism ? And can you tell me is there a successful case that U-Boot on 750FX or 750 can handle the exceptions normally? Thanks a lot for your reply.
Best regards, gaohai
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