Dear all,
I have the follwing few queries in setup.S,please help !
a) If it is big kernel ,it is loaded at 1 MB but in real mode we can
access only up to 1 MB then how is it loaded above 1 MB ? i guess
i made some mistake in understanding the code here.
b) The code for loading the GDT address and limit in GDTR
is .word 0x800 ! gdt limit=2048, 256 GDT entries
.word 512+gdt,0x9 ! gdt base = 0X9xxxx
why add 512 to gdt ?
access only up to 1 MB then how is it loaded above 1 MB ? i guess
i made some mistake in understanding the code here.
b) The code for loading the GDT address and limit in GDTR
is .word 0x800 ! gdt limit=2048, 256 GDT entries
.word 512+gdt,0x9 ! gdt base = 0X9xxxx
why add 512 to gdt ?
c) All the interrupts are masked of during the programming of PIC-8259,but
before this itself the IDTR is loaded with a base and limit value 0,now
if an interrupt occurs between the loading of IDTR with the
above base and limit values and programming the PIC ,won't it result in
an exception ? i mean is it not necessary to mask off the interrupts
before loading IDTR.
before this itself the IDTR is loaded with a base and limit value 0,now
if an interrupt occurs between the loading of IDTR with the
above base and limit values and programming the PIC ,won't it result in
an exception ? i mean is it not necessary to mask off the interrupts
before loading IDTR.
d) Next i am planning to go thru head.S but i can find two head.S
ie
arch/i386/boot/compressed/head.S
arch/i386/kernel/head.S
arch/i386/boot/compressed/head.S
arch/i386/kernel/head.S
why two head.S ?
Thanks for all the help received earlier
gkumar
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