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Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 6:10 am
by ~
Is there some known BIOS binary code or some possibility that BIOS INT calls such as video, disk, network, USB or other "advanced" services (or any other INTs) switch to protected mode when they are called for something like changing the video resolution?
Are there some BIOSes or peripherals known to switch to "full" 32 or 16-bit protected mode natively at some point in their BIOS services?
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 6:15 am
by quanganht
AFAIK, no.
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 6:30 am
by madeofstaples
Well there's
INT 15/AH=89h...
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 8:28 am
by quanganht
Lol, an interrupt used to enable Pmode. Why do people only talk about far jump but not this one?
Edit: I think the original author want to ask weather there is an interrupt that enter Pmode when it is executing and return back to realmode when it has done it's job. In this case, no.
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 10:37 am
by tantrikwizard
Not exactly what you're looking for but the VBE standard has some 32bit pmode functions for some video related functions. Initially execute interrupts in real mode to retrieve the pmode interface then after entering pmode the functions are called directly.
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 12:40 pm
by Dex
I think you will find int's like int 15h do.
Re: Do you know 32-bit code in BIOS INTs?
Posted: Fri Dec 18, 2009 12:44 pm
by Gigasoft
BIOSes can only use protected mode during booting, and they often do so to copy PCI boot ROMs into low memory, for example. If they enter protected mode after booting, it would break systems that call the BIOS in V86 mode.
Re: Do you know 32-bit code in BIOS INTs?
Posted: Sat Dec 19, 2009 9:58 am
by Lithorien
Woah! Why don't people use this to get to pmode instead of that far jump / manual IRQ remapping method?
Re: Do you know 32-bit code in BIOS INTs?
Posted: Sat Dec 19, 2009 10:44 am
by earlz
Lithorien wrote:
Woah! Why don't people use this to get to pmode instead of that far jump / manual IRQ remapping method?
It looks like it may be vendor specific; as in, there is a reason you have never heard of it...
I think this may have a good use in some 512 byte competitions
Re: Do you know 32-bit code in BIOS INTs?
Posted: Sun Dec 20, 2009 6:18 pm
by jal
quanganht wrote:Edit: I think the original author want to ask weather there is an interrupt that enter Pmode when it is executing and return back to realmode when it has done it's job. In this case, no.
Of course it's yes. XMS handling (e.g.
int 15h/ah=87h) must do so to access extended memory. I'm not entirely sure whether there's BIOSes that have these services natively, i.e. without some HIMEM.SYS loaded, though RBIL seems to suggest there are:
RBIL wrote:Copy is done in protected mode with interrupts disabled by the default BIOS handler
JAL
Re: Do you know 32-bit code in BIOS INTs?
Posted: Mon Dec 28, 2009 8:37 pm
by Love4Boobies
I'm not a necro but...
jal wrote:Of course it's yes. XMS handling (e.g.
int 15h/ah=87h) must do so to access extended memory.
I saw this post and remember trying to answer the exact same thing. jal beat me to it because chase won't give up that stupid Spamhaus crap.
earlz wrote:Lithorien wrote:
Woah! Why don't people use this to get to pmode instead of that far jump / manual IRQ remapping method?
It looks like it may be vendor specific; as in, there is a reason you have never heard of it...
It's not. It's defined by the IBM Personal Computer Standard 2.