RE: [Xpert]256 megs board fails Validation,

[Alexander Stohr]

Title: RE: [Xpert]256 megs board fails Validation,

and thats with boards that can handle bus width with chunks of 256 bit = 32 byte per access cylce.

 

i think i do generally object to using signed numbers for ordinal values. ;-)

 

if there is really a limitiation,

then its the question if changing the concept (32 Byte chunks, 1 Byte chunks, whatever)

or if changing the possible range of the value (e.g. unsigned long long = 64 bits counter).

-----Original Message-----
From: Luugi Marsan [mailto:[EMAIL PROTECTED]]
Sent: Monday, November 04, 2002 23:38
To: [EMAIL PROTECTED]
Subject: Re: [Xpert]256 megs board fails Validation,

I understand, but 256 megs = 256 * 1024 * 1024* 8 bits = 2^ 31 bits= 2147483648. The Xserver calculates the memory in bits when validating the mode.

Luugi

Alexander Stohr wrote:

sorry, but your number theory has some error.

2^1 = 2 (1 bit, counting from 0 to 1 => 2 values)
2^2 = 4 (2 bits, counting from 0 to 3 => 4 values)
2^4 = 8 (3 bits counting from 0 to 7 => 8 values)
[...]
2^31 = 2 GB
2^32 = 4 GB

an integer with 32 bits has 1 bit sign and 31 bits for numeric value.
this is (-2GB) to (+2GB-1).
so your 256 MB limit must arise from somewhere else.

for your case you should better starting the printf debugger
or real debugging. maybe PCI or AGP config caps, or MTRR caps
are the limiting factor, or its just a driver bug. (wild guessing)

-Alex.

> -----Original Message-----
> From: Luugi Marsan [mailto:[EMAIL PROTECTED]]
> Sent: Monday, November 04, 2002 21:33
> To: [EMAIL PROTECTED]
> Subject: [Xpert]256 megs board fails Validation,
>
>
> Hi,
>
> There's a problem when validating a given mode. The board I
> have has 256
> megs and it fails crying that it has insufficient memory for
> the given
> mode. This happens because the videoRam in bits is equal to
> 2^31 ( 256
> megs).  The number passes the numerical limit of an "int". I believe
> that the videoRam should be an "unsigned int" instead of a
> signed "int".
> What do you think? Will this change create other problems?
>
> Y2K all over again. :)
>
> Luugi
>
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