More Chipram

[Piru]

@KThunder

yes exactly if you are trying to use above 2meg as ram you dont want the custom chips to do anything right, you want them to share the bus with the cpu. you dont need the custom chips to do anything with above 2meg do you you just want to use the ram for the cpu for programs

And this is: fast memory.

So what's the point in trying to make it chip memory, again?

[Karlos]

@KThunder

"So you get a system with >2MB chipram that can't be used by the custom chips" - meaning they can't use the area > 2MB, not  that they can't use any chip ram at all.

The problem is, what happens when the OS allocates chip memory above 2MB space for the bitplane data of a screen you just opened? Your snooper prevents the hardware from doing anything when it tries to fetch the data. So you just get a totally black screen (if you are lucky, I am sure things would crash long before getting even this far) ?

As for using the memory for program code etc, why? This is what fast ram is for.

[KThunder]

some programs need chip memory for certain functions, amigaos loads certain things into chip ram yes. if you are trying (like some people) to run too many programs and the os needs more chip ram you are stuck. what does the custom chips in winuae use the upper parts of 8meg for? not much id wager because the os commands those chips to do stuff right. the os can use up to 8megs for lots of stuff though

why would the os allocate bitplane space up at 7meg or so? it wouldnt or wouldnt have to anyway

[Karlos]

Can you give an example of anything the OS specifically puts into chip ram (on any machine having adequate fast ram) that isn't put there so the custom chips can use it for some purpose?

[KThunder]

wait... screens i see what you mean, im thinking in terms of programs but the os could put screens up there couldnt it

your stack is in chip ram, so are major parts of the os, as are any old programs and all data concerning what programs are loaded and where they are, multitasking info etc.

[Piru]

@KThunder

some programs need chip memory for certain functions, amigaos loads certain things into chip ram yes.

But they load these things to chip memory for a reason: These things are to be processed using the custom chips.

if you are trying (like some people) to run too many programs and the os needs more chip ram you are stuck.

Tough. You're supposed to free some memory and try again. Or reboot.

what does the custom chips in winuae use the upper parts of 8meg for? not much id wager because the os commands those chips to do stuff right.

The OS sees absolutely no difference in the memory below or above 2MB, there is no special treatment. It's exactly the same as the lower parts, it's regular chip memory. It can be used for display, blitter, paula audio, floppy DMA etc.

This works in WinUAE because it a) has chipset emulation that can handle upto 8MB chip memory b) it has resident tag that AddMemList the additional chip memory to system.

[Karlos]

KThunder wrote:
wait... screens i see what you mean, im thinking in terms of programs but the os could put screens up there couldnt it

The OS would look only for MEMF_CHIP for the displayable bitplane data on your 8MB system. Now if you already gobbled up your lower 2MB with 3 instances of Scala, it isnt going to not allocate it above 2MB if space exists there.

[Piru]

@KThunder

wait... screens i see what you mean, im thinking in terms of programs but the os could put screens up there couldnt it

No it couldn't. Or at least it would be no different from fast memory. You'd still need to swap the memory in & out, which is really painfully slow with chip memory. And OS doesn't do this anyway, it assumes MEMF_CHIP is displayable.

[KThunder]

yeah the os allocating some stuff in upper chip ram would muck stuff upp. at best it would be like slow ram or something. not completely usable, fast ram is better

[Karlos]

KThunder wrote:

your stack is in chip ram, so are major parts of the os, as are any old programs and all data concerning what programs are loaded and where they are, multitasking info etc.

Holy smokes, your amiga must be dead slow then. On mine, all this data goes right into fast ram where the 68040 can access it every cycle ;-)

[KThunder]

actually it doesnt. you can use mmu to remap rom to fast ram but alot of this stuff goes into chip

[Piru]

@KThunder

your stack is in chip ram, so are major parts of the os

No way, they aren't. This stuff is in the fastest memory possible (highest priority).

, as are any old programs

Only some very very very old and buggy (I'd say -86 or so apps).

and all data concerning what programs are loaded and where they are, multitasking info etc.

No, nothing of this sort is in chip memory. This stuff is kept in fastest memory possible.

you can use mmu to remap rom to fast ram but alot of this stuff goes into chip

The only situation things like supervisor stack and exec.library can end up in chip memory is due to lame accelerator adding memory to system too late, so that the exec.library relocation code can't see it. And anyway, there are patches to fix this (FastExec, BK's LocalFast).

[Karlos]

Nope, I have the following all in fast (and the address ranges to prove it)

Kickstart
Exec
Supervisor Stack Pointer
User Stack Pointer
Vector Base Register

[KThunder]

Piru wrote:
@KThunder

wait... screens i see what you mean, im thinking in terms of programs but the os could put screens up there couldnt it

No it couldn't. Or at least it would be no different from fast memory. You'd still need to swap the memory in & out, which is really painfully slow with chip memory. And OS doesn't do this anyway, it assumes MEMF_CHIP is displayable.

in winuae if you have 8megs chip and you start up a crapload of programs screens ight get put up above 2meg right? that would cause problems right if you flipped screens or doesnt it work that way?

[KThunder]

so you guys have nothing in chip ram huh, nothing at all not a single byte used?
what is this thread here for then if noone uses chip ram

[Karlos]

On UAE its fine because UAE emulates custom chips that were never actually made in real life that are capable of using all 8MB of chip ram. So everything is just fine.

Of course setting 8MB of chip reduces your Z2 space as you might notice. On a real amiga this could be problematic as a lot of expansions want to live there.