[Gllug] Wrong "mem=XXXm" makes kernel *slow*?

[John Winters]

On Thu, 2005-02-24 at 02:48 +0000, Mike Brodbelt wrote:
> On Wed, 2005-02-23 at 12:32 +0000, Christian Smith wrote:
> > On Tue, 22 Feb 2005, Mike Brodbelt wrote:
[snip]
> > It appears you have a chipset which has built in video which shares memory
> > with main memory, you're probably experiencing contention for memory
> > access with the video circuitry.
> 
> While I can't speak for John's machine, mine does not have on board
> video, has a separate AGP graphics card, and I'm aware of no reason why
> there might conceivably be contention. The boot speed is extremely slow
> with highmem support in the kernel - definitely not faster than one can
> follow on screen. To boot from cold to an X login took upwards of 10
> minutes, IIRR.

Mine does have on-board video - albeit disabled.  The video is handled
by a PCI NVidia card.  Unfortunately the BIOS does not allow the RAM
reserved for on-board video to be reduced below 8M.

> > Hence the nice round 32MB before things
> > normalise again. Either live with it, or buy a cheap PCI/AGP GFX card and
> > disable the onboard GFX.
> 
> In my case at least, I don't think video contention is the cause of this
> problem.

Certainly not the full explanation.  The 32M boundary does seem to be
some sort of fixed magic number though.

Note - when the machine had 512M of RAM, everything just worked
(including the 8M of reserved RAM) without the need for any boot-time
parameters.

John

-- 
John Winters <john at sinodun.org.uk>

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