flat assembler
Message board for the users of flat assembler.

Index > OS Construction > PM32: CPL0 > CPL3 > INT xx !> incorrext

Author
Thread Post new topic Reply to topic
omegicus



Joined: 16 Jul 2013
Posts: 8
Location: Ukraine
omegicus 16 Jul 2013, 11:31
Hi all!
Can anyone help or any idea about possible bugs (theoretical):

I have 32bit OS in PM32 with GDT: R0C, R0D, R3C, R3D.
When i call R3C code - all works fine, then i call my int 0x27 to put string - all fine. But when i try to int 0x27 for GetChar - it returns incorrect data. When this code works in R0C all ws fine. So problem 100% in Interrupt R0C > Task R3C fragment. TSS correct (becouse in software multitasking R3C > R0C transition works propertly.)

What is the question: have anyone an idea or something to how to INTR must finish itself on Ring0 if it was called from Ring3???

Question Shocked Sad [/b]
Post 16 Jul 2013, 11:31
View user's profile Send private message Reply with quote
nop



Joined: 01 Sep 2008
Posts: 165
Location: right here left there
nop 17 Jul 2013, 05:49
welcome to fasm board omegicus sory i dont know bout pm ring stuf but im sure somebody wil help u soon Wink
Post 17 Jul 2013, 05:49
View user's profile Send private message Reply with quote
cod3b453



Joined: 25 Aug 2004
Posts: 618
cod3b453 17 Jul 2013, 16:54
When you say "incorrect data" what is incorrect? i.e. which registers or memory regions?

It may be worth looking at the hardware task switching/task management sections in the Intel/AMD system programming manuals, if you haven't already.
Post 17 Jul 2013, 16:54
View user's profile Send private message Reply with quote
omegicus



Joined: 16 Jul 2013
Posts: 8
Location: Ukraine
omegicus 17 Jul 2013, 18:28
i mean: in R0 to R0 state i getting IRQ1 (keyboard) key in AL register. all works fine.
But when R0 INT to R3 code: al contains some incorrect data, not key state....

It is not so important question, some way i will do it))), but it's a time.......(((

I thought may be someone have relat. problems... and have an answer...
Post 17 Jul 2013, 18:28
View user's profile Send private message Reply with quote
baldr



Joined: 19 Mar 2008
Posts: 1651
baldr 17 Jul 2013, 18:42
omegicus,

It should be guesswork? Show some relevant code/data.
Post 17 Jul 2013, 18:42
View user's profile Send private message Reply with quote
omegicus



Joined: 16 Jul 2013
Posts: 8
Location: Ukraine
omegicus 17 Jul 2013, 18:58
terminal.exe:
.char:
mov eax, OM_F_GETC
int 0x27
or al, al
jz .char
mov bl, al



int27.inc: ; this code get byte from keyboard and put result in AL... in CPL0 -> CPL0 all works fine
ALIGN 4
I_27:
CLI
....
STI
IRETD


IRQ1.inc: ; keyboard handler
ALIGN 4
IRQ1:
CLI
PUSHAD
PUSH DS ES FS GS
CLD

MOV AX, CORE_DS
MOV DS, AX
...

IN AL, 0x61 ; give finishing information
OUT 0x61, AL ; to keyboard...
EINTRM
POP GS FS ES DS
POPAD
STI
IRETD


i don't know what to show... there are lot of code...
while i not turn on Ring3 mode all worked super fine!
Fact1: standart INT works correctly while not needed to return some data to Ring3 back (for example, PrintString via INT works correctly)
Fact2: IRQ0 (Scheduler) works correct anyway: it's switch tasks (Ring0 and Ring3) and working in Ring0 too... all ok.

I have only one idea: maybe INT (R0) must detect from what CPL was interrupt called... and if it was not R0 modify return stack from just EIP/CS/EFLAGS to EIP/CS/EFLAGS/ESP/SS... before IRET call... such as in Scheduler... i'll try this soon and if it IS i'll write about...
Post 17 Jul 2013, 18:58
View user's profile Send private message Reply with quote
omegicus



Joined: 16 Jul 2013
Posts: 8
Location: Ukraine
omegicus 18 Jul 2013, 07:11
ohohoh!!!

cool... i understood!

thats was becouse i forot about my mouse driver... it was loaded as mice.exe (such a program resident, it detects mice and install's IRQ12). Becouse I turned on Ring3 -> this code now in Ring3 -> IRQ not in CPL0...

so when i disabled mice.exe loading my code starts working fine.


it's my fault to do something and then modify core... i should have to make Ring3 code and just then make drivers and so.... Sad
Post 18 Jul 2013, 07:11
View user's profile Send private message Reply with quote
Display posts from previous:
Post new topic Reply to topic

Jump to:  


< Last Thread | Next Thread >
Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Copyright © 1999-2024, Tomasz Grysztar. Also on GitHub, YouTube.

Website powered by rwasa.