[U-Boot-Users] Virtex-II Pro and Instruction Prefetching
Hello,
I'm working on getting PPCBoot 2.0.0 and Linux running on a custom Virtex-II Pro development board.
I'm currently encountering problems with my DDR SDRAM controller -- it can't seem to handle instruction prefetching yet. So to sidestep the issue for now, I want to configure the 405 so that instructions are not prefetched.
I've disabled instruction caching altogether (ICCR = 0x00000000) and I have a core configuration register (CCR0) value of 0x00700000, which according to the documentation has "prefetching for non-cachable regions" disabled.
Even so, ChipScope is telling me that instructions are still being prefetched from SDRAM (sometimes 2 instructions, sometimes 4, and sometimes 8 instructions at a time). Is there anything else I have to do to disable prefetching of non-cachable instructions?
Thanks, Frank.
On Sat, Jun 14, 2003 at 09:27:14AM -0300, Frank Smith wrote:
I'm working on getting PPCBoot 2.0.0 and Linux running on a custom Virtex-II Pro development board.
Forget that old version. Use U-Boot and start with the latest release or with CVS.
Robert
In message 03Jun14.092013adt.7305@dragon.appliedmicro.ns.ca you wrote:
I'm working on getting PPCBoot 2.0.0 and Linux running on a custom Virtex-II Pro development board.
May I ask why you use PPCBoot (a dead project) instead of the successor project U-Boot?
I'm currently encountering problems with my DDR SDRAM controller --
This is a very common problem. Seems 99% of all people who attempt to port U-Boot see this soner or later.
it can't seem to handle instruction prefetching yet. So to sidestep the issue for now, I want to configure the 405 so that instructions are not prefetched.
Don't. The problem will bit you later again. Solve problems as they appear.
Wolfgang Denk
On Sat, 14 Jun 2003, Wolfgang Denk wrote:
In message 03Jun14.092013adt.7305@dragon.appliedmicro.ns.ca you wrote:
I'm working on getting PPCBoot 2.0.0 and Linux running on a custom Virtex-II Pro development board.
May I ask why you use PPCBoot (a dead project) instead of the successor project U-Boot?
Just haven't gotten around to it. I promise I will soon (although I think there's a bug in cpu/ppc4xx/start.S I've pointed out previously that nobody has rendered an opinion on as of yet :-)
I'm currently encountering problems with my DDR SDRAM controller --
This is a very common problem. Seems 99% of all people who attempt to port U-Boot see this soner or later.
it can't seem to handle instruction prefetching yet. So to sidestep the issue for now, I want to configure the 405 so that instructions are not prefetched.
Don't. The problem will bit you later again. Solve problems as they appear.
Point taken. I've identified the problem, and someone else is working on solving it, so I'm just looking for a way to make some progress until it gets solved.
Thanks, -Frank.
In message 03Jun14.105725adt.7305@dragon.appliedmicro.ns.ca you wrote:
May I ask why you use PPCBoot (a dead project) instead of the successor project U-Boot?
Just haven't gotten around to it. I promise I will soon (although I think
Do it now. Don't waste time on old stuff.
there's a bug in cpu/ppc4xx/start.S I've pointed out previously that nobody has rendered an opinion on as of yet :-)
You mean the STD_EXCEPTION vs. CRIT_EXCEPTION ?
I am waiting for Stefan to pick this up :-)
But actually it should not matter at all: your code is never supposed to run into such an exception. If it's crashing anyway there is little difference if it's crashing "correctly" or not ;-)
Best regards,
Wolfgang Denk
-----Original Message----- From: wd@denx.de [mailto:wd@denx.de]
there's a bug in cpu/ppc4xx/start.S I've pointed out previously that nobody has rendered an opinion on as of yet :-)
You mean the STD_EXCEPTION vs. CRIT_EXCEPTION ?
I am waiting for Stefan to pick this up :-)
But actually it should not matter at all: your code is never supposed to run into such an exception. If it's crashing anyway there is little difference if it's crashing "correctly" or not ;-)
The problem with it crashing incorrectly is that the Oops message lies to you, as it's reporting the contents of SRR0/SRR1, not SRR2/SRR3 as it should be for a critical exception. Makes it more difficult to debug when you think the wrong instruction is causing the exception.
Thanks, -Frank. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.488 / Virus Database: 287 - Release Date: 6/5/03
Hi!
there's a bug in cpu/ppc4xx/start.S I've pointed out previously that nobody has rendered an opinion on as of yet :-)
You mean the STD_EXCEPTION vs. CRIT_EXCEPTION ?
I am waiting for Stefan to pick this up :-)
But actually it should not matter at all: your code is never supposed to run into such an exception. If it's crashing anyway there is little difference if it's crashing "correctly" or not ;-)
The problem with it crashing incorrectly is that the Oops message lies to you, as it's reporting the contents of SRR0/SRR1, not SRR2/SRR3 as it should be for a critical exception. Makes it more difficult to debug when you think the wrong instruction is causing the exception.
OK, this seems to be correct. Let's give it a try!
Best regards, Stefan.
participants (4)
-
Frank Smith -
Robert Schwebel -
Stefan Roese -
Wolfgang Denk