Messages in this thread |  | | Date | Sat, 22 Dec 2001 17:13:18 +0100 (CET) | From | Robert Schwebel <> | Subject | Re: AMD SC410 boot problems with recent kernels |
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On Fri, 21 Dec 2001, H. Peter Anvin wrote: > > there are boot problems with new kernels on AMD SC410 processors. > > "On one particular SC410 board."
Ok, but it's one of the most widespread embedded x86 boards in Europe.
> The loop counter you're outputting is the 2nd byte of the loop counter, > which really isn't interesting;
This was just from the last test: the result was %ch=0 and %cl=1.
> what probably makes more sense to output is the value of %dx in your > code.
%dx? Do you mean %cx or do I not understand the code? ;)
> I would like to suggest making the following changes and try them out: > > a) Change A20_TEST_LOOPS to something like 32768 in the new kernel code.
Still reboots.
> b) Add a "call delay" between the movw and the cmpw in your old_loop > and see if it suddenly breaks;
No, it still works.
> c) Check what your %dx value is (if it's nonzero, there might be an > issue.)
I assume you mean in my old_wait code, at the lines where I give out the stuff to the LED ports? Neither %dl nor %dh has something different from 0 here. How could something come into %dx here?
> d) Once again, please complain to your motherboard/BIOS vendor and tell > them to implement int 15h, ax=2401h.
I'll do that, but this won't help for the hundrets of boards which are still out there and worked fine with the previous code...
> e) Add a strictly serializing instruction sequence, such as: > > pushw %dx > smsw %dx > lmsw %dx > popw %dx > > ... where the "call delay" call is in a20_test.
Hope I understand you correctly - I'm not an assembler wizzard yet ;) Is this correct:
----------8<---------- a20_test: pushw %cx pushw %ax xorw %cx, %cx movw %cx, %fs # Low memory (segment 0x0000) decw %cx movw %cx, %gs # High memory area (segment 0xffff) movw $A20_TEST_LOOPS, %cx movw %fs:(A20_TEST_ADDR), %ax # put content of test address... pushw %ax # ... on stack a20_test_wait: incw %ax movw %ax, %fs:(A20_TEST_ADDR)
pushw %dx smsw %dx
call delay # Serialize and make delay constant
lmsw %dx popw %dx
cmpw %gs:(A20_TEST_ADDR+0x10), %ax loope a20_test_wait
popw %fs:(A20_TEST_ADDR) popw %ax popw %cx ret ---------->8----------
Still reboots with this code.
Robert -- +--------------------------------------------------------+ | Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de | | Pengutronix - Linux Solutions for Science and Industry | | Braunschweiger Str. 79, 31134 Hildesheim, Germany | | Phone: +49-5121-28619-0 | Fax: +49-5121-28619-4 | +--------------------------------------------------------+
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