My OS can only see ~3 GiB

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

My 64 Bit OS can only detect ~3-3.5 GiB ram
If I use VBox it sees 3.5G if I use Qemu it only sees 3G
My bootloader uses the INT 0x15, EAX = 0xE820 method to detect ram

I have no other information, and am lost im this mess.

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

Are you collecting the entire memory map?

Are you reading all 64 bits of the addresses?

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

I belive so, I send peramitors to the bios and send a pointer to the result to the kernel

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

Have you tried looking at the memory map? Like, by printing it or something?

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

Yes, not priting the full thing but i did a print out of lengths and it shows exactly why my OS detects

I am trying to work throught my boot code and do some checks there but I still have not found a solution

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

How much RAM did you configure in those VMs?

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

i have tride at 4G but am curently trying with 8G
I have tride between 32M and 24G in Vbox yet it only works up to 3.5G

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

Can you print the whole memory map and share it?

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

Also VBox will freeze during initiation of page tables when its using more than 3GiB
And I just noticed it crashes if I use exactly 2G

This is only in VBox

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

Octocontrabass wrote:

Can you print the whole memory map and share it?

I can try but I will need to try to fix my crash problem too, as it messes with output

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

VBox halts apon:

Code:

gas("movq %0, %%cr3" : : "r" (pt) :);

when I am using more than 1G ram

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

Does VBox not suport 1GiB pages???

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

well iv figured out vbox, but not why i cant see more memory hm

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

Xeno wrote:

Does VBox not suport 1GiB pages???

It's an optional feature, you need to check CPUID before you try to use it.

Xeno · **Joined:** Tue Oct 10, 2023 7:40 pm **Posts:** 51

Octocontrabass wrote:

Xeno wrote:

Does VBox not suport 1GiB pages???

It's an optional feature, you need to check CPUID before you try to use it.

I realized
my code is bad -_-
Im still not able to fuigure out the first problem

OSDev.org

My OS can only see ~3 GiB

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