[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios
From: |
H. Peter Anvin |
Subject: |
Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios |
Date: |
Mon, 11 Oct 2010 14:51:40 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc13 Thunderbird/3.1.4 |
On 10/11/2010 02:41 PM, Sebastian Herbszt wrote:
> H. Peter Anvin wrote:
>> On 10/11/2010 01:30 PM, Anthony Liguori wrote:
>>> On 10/11/2010 02:59 PM, Gleb Natapov wrote:
>>>> No boot rom should do that. extboot wreaks havoc when it is used.
>>>> And since virtio is now supported by bios there is no reason to use it.
>>>
>>> You don't really have a choice. You could be doing hardware passthrough
>>> and the ROM on the card may hijack int19.
>>
>> The BBS standard actually documents how to deal with that -- it pretty
>> much works out to "let the card initialize, then see if it mucked with
>> int19, and then put int19 back... if we want to run that card, then we
>> invoke the int19 that the card set up."
>
> The BIOS Boot Specification, Version 1.01 from January 11, 1996 seems not to
> recommend this:
>
> 3.4 Legacy IPL Devices
>
> "Legacy IPL devices will be allowed to take control of the system (via hooking
> interrupts) in both Legacy and PnP systems. The Plug and Play BIOS
> specification
> recommends that Legacy devices that hook a bootstrap interrupt such as INT
> 19h, 18h,
> or 13h have the interrupt re-captured by the BIOS. This is not done because
> grabbing
> an interrupt vector back after a device has hooked it can produce
> unpredictable results.
> Further, by allowing the card to take control, the behavior of these Legacy
> cards will
> be the same on both PnP and Legacy machines."
>
> 6.8 Notes on the POST Process
>
> "The Plug and Play BIOS Specification says that if a Legacy IPL device's
> option
> ROM captures INT 18h or INT 19h, the BIOS should save this vector and then
> restore the original one put there by the BIOS. The BIOS Boot Specification
> deviates from this in that these vectors are not recaptured after each Legacy
> option
> ROM returns from initialization. That would be considered unsafe."
>
Sorry, you're right -- I confused the PNPBIOS spec with the BBS spec
(and compounded the error by correctly remembering that BBS overrides
PNPBIOS).
-hpa
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, (continued)
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gerd Hoffmann, 2010/10/11
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Sebastian Herbszt, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios,
H. Peter Anvin <=
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/12
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/13
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/13
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/13