[LinuxBIOS] Problems with Filo booting - HELP

joe at smittys.pointclark.net joe at smittys.pointclark.net
Tue Oct 2 04:09:40 CEST 2007

Quoting Jordan Crouse <jordan.crouse at amd.com>:

> On 01/10/07 21:06 -0400, joe at smittys.pointclark.net wrote:
>> Quoting ron minnich <rminnich at gmail.com>:
>> > On 10/1/07, joe at smittys.pointclark.net <joe at smittys.pointclark.net> wrote:
>> >
>> >> c. It is located in the second slot not first.
>> >
>> > hmm. could this second slot somehow have a different base physical
>> > address? unlikely but this is getting confusing.
>> >
>> > ron
>> >
>> I don't think so. Your telling me. I am so confused right now I'm
>> starting to get a migrane. I can't for the life of me figure out why
>> this is choking. Everything seems to be ok right up to the
>> jmp_to_elf_entry() function. Then it chokes at the assembly part. Does
>> that make sense??
> Absolutely - if your memory is hosed, this will be the first place that
> you'll run afowl of it, especially when it comes to the top of memory.
> Because whats happening at this point is that LinuxBIOS is copying some
> part of itself to the top of memory to make room for the payload.  If
> your memory map is wierd, then this will easily be the first place where
> it will be exposed.
> Jordan
LinuxBIOS does get copied to TOM? From looking at the code it just  
looks like it just doubles LB's size and then copies it there (bounce  
buffer). If it is getting copied to TOM that explains everything. The  
Internal graphics is supposed to pre-allocate memory from TOM down.  
 From the i82830 datasheet:

These Register Bits control the theft of memory from Main Memory space  
for use as Graphics memory. The memory for TSEG is pre-allocated first  
and then the Graphics memory is pre-allocated. An example of this  
theft mechanism is:

TOM equal 64 MB,
TSEG selected as 512 KB in size,
Graphics memory selected as 1 MB in size
General System RAM available in system = 62.5 MB
General System RAM Range             00000000h to 03E7FFFFh
TSEG Address Range                   03F80000h to 03FFFFFFh
TSEG pre-allocated from              03F80000h to 03FFFFFFh
Graphics memory pre-allocated from   03E80000h to 03F7FFFFh

I don't have TSEG enabled though. I wonder if I did though, it would  
give LB extra space for it's bounce buffer?? Does this make any sense?

Thanks - Joe

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