Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 11:07:08PM -0500, Kevin O'Connor wrote: ... hardware. Maybe we could poke someone from KVM camp for a hint? SeaBIOS has two ways to be deployed - first is to copy the image to the top of the first 1MB (eg, 0xe-0xf) and jump to 0xf000:0xfff0 in 16bit mode. The second way is to use the SeaBIOS elf and deploy into memory (according to the elf memory map) and jump to SeaBIOS in 32bit mode (according to the elf entry point). SeaBIOS doesn't really need to be in the top 4G of ram. SeaBIOS does expect to have normal PC hardware devices (eg, a PIC), though many hardware devices can be compiled out via its kconfig interface. The more interesting challenge will likely be in communicating critical pieces of information (eg, total memory size) into SeaBIOS. The SeaBIOS mailing list (seab...@seabios.org) is probably a better location for technical seabios questions. Hi Kevin, thanks for pointing. Yes, providing info back to seabios to setup mttr and such (so seabios would recognize them) is most challeging I think. Cyrill -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 1:03 PM, Yang Bai hamo...@gmail.com wrote: Since on X86, bios is always at the end of the address space, so I have some thought about how to implement the seabios support for kvm tool. 1. using kvm__register_mem to map the end of address space to the guest then copy the code of seabios to this mem region. Just emulating the bios chip. 2. leave the bios code alone and don't touch the guest's address space. If the guest accesses the address belonging to the bios, it will be an IO request and we can emulate the IO access to the bios chip. Any ideas about this? The latter solution doesn't make any sense to me. Cyrill, do we really need to put the BIOS at the end of the address space? Don't we have unused space below 1 MB? And question: How could I set the first instruction address after we issue the vmlaunch instruction? You need to set -boot_ip and fiends. See tools/kvm/x86/kvm.c::load_bzimage() for an example. Pekka -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 01:10:59PM +0200, Pekka Enberg wrote: On Tue, Feb 14, 2012 at 1:03 PM, Yang Bai hamo...@gmail.com wrote: Since on X86, bios is always at the end of the address space, so I have some thought about how to implement the seabios support for kvm tool. 1. using kvm__register_mem to map the end of address space to the guest then copy the code of seabios to this mem region. Just emulating the bios chip. I think this is what should be done. 2. leave the bios code alone and don't touch the guest's address space. If the guest accesses the address belonging to the bios, it will be an IO request and we can emulate the IO access to the bios chip. Any ideas about this? The latter solution doesn't make any sense to me. Cyrill, do we really need to put the BIOS at the end of the address space? Don't we have unused space below 1 MB? I don't remember for sure how SeaBIOS works actually. What I rememer is that it aquires all hw environment might have. So without real look into seabios code I fear I can't answer. But reserving end of 4G address space for bios copy sounds reasonable if we going to behave as real hardware. Maybe we could poke someone from KVM camp for a hint? Cyrill -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 09:20:18PM +0800, Yang Bai wrote: And will seabios replace the present bios implement or co-exsit? Ideally we should get rid of our minibios completely and only have seabios here instead. Cyrill -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On 02/14/2012 07:03 PM, Yang Bai wrote: Hi all, Since on X86, bios is always at the end of the address space, so I have some thought about how to implement the seabios support for kvm tool. 1. using kvm__register_mem to map the end of address space to the guest then copy the code of seabios to this mem region. Just emulating the bios chip. 2. leave the bios code alone and don't touch the guest's address space. If the guest accesses the address belonging to the bios, it will be an IO request and we can emulate the IO access to the bios chip. Any ideas about this? Can I ask what's the purpose of mapping BIOS code to guest? Any usage? Shouldn't BIOS's behavior be emulated by hypervisor? Thanks. -cody And question: How could I set the first instruction address after we issue the vmlaunch instruction? Thanks, Yang -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 09:20:18PM +0800, Yang Bai wrote: And will seabios replace the present bios implement or co-exsit? On Tue, Feb 14, 2012 at 3:32 PM, Cyrill Gorcunov gorcu...@openvz.org wrote: Ideally we should get rid of our minibios completely and only have seabios here instead. No, no, they should co-exist. There's absolutely no reason to force people to use a BIOS to boot Linux. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 05:35:47PM +0200, Pekka Enberg wrote: On Tue, Feb 14, 2012 at 09:20:18PM +0800, Yang Bai wrote: And will seabios replace the present bios implement or co-exsit? On Tue, Feb 14, 2012 at 3:32 PM, Cyrill Gorcunov gorcu...@openvz.org wrote: Ideally we should get rid of our minibios completely and only have seabios here instead. No, no, they should co-exist. There's absolutely no reason to force people to use a BIOS to boot Linux. I meant run-time (ie in memory). I didn't mean substitude our minibios, but rather have an ability to either run with compiled-in bios or with seabios instead. Cyrill -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 5:38 PM, Cyrill Gorcunov gorcu...@openvz.org wrote: Ideally we should get rid of our minibios completely and only have seabios here instead. No, no, they should co-exist. There's absolutely no reason to force people to use a BIOS to boot Linux. I meant run-time (ie in memory). I didn't mean substitude our minibios, but rather have an ability to either run with compiled-in bios or with seabios instead. Sure. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: The way of mapping BIOS into the guest's address space
On Tue, Feb 14, 2012 at 04:13:42PM +0400, Cyrill Gorcunov wrote: On Tue, Feb 14, 2012 at 01:10:59PM +0200, Pekka Enberg wrote: On Tue, Feb 14, 2012 at 1:03 PM, Yang Bai hamo...@gmail.com wrote: Since on X86, bios is always at the end of the address space, so I have some thought about how to implement the seabios support for kvm tool. 1. using kvm__register_mem to map the end of address space to the guest then copy the code of seabios to this mem region. Just emulating the bios chip. I think this is what should be done. 2. leave the bios code alone and don't touch the guest's address space. If the guest accesses the address belonging to the bios, it will be an IO request and we can emulate the IO access to the bios chip. Any ideas about this? The latter solution doesn't make any sense to me. Cyrill, do we really need to put the BIOS at the end of the address space? Don't we have unused space below 1 MB? I don't remember for sure how SeaBIOS works actually. What I rememer is that it aquires all hw environment might have. So without real look into seabios code I fear I can't answer. But reserving end of 4G address space for bios copy sounds reasonable if we going to behave as real hardware. Maybe we could poke someone from KVM camp for a hint? SeaBIOS has two ways to be deployed - first is to copy the image to the top of the first 1MB (eg, 0xe-0xf) and jump to 0xf000:0xfff0 in 16bit mode. The second way is to use the SeaBIOS elf and deploy into memory (according to the elf memory map) and jump to SeaBIOS in 32bit mode (according to the elf entry point). SeaBIOS doesn't really need to be in the top 4G of ram. SeaBIOS does expect to have normal PC hardware devices (eg, a PIC), though many hardware devices can be compiled out via its kconfig interface. The more interesting challenge will likely be in communicating critical pieces of information (eg, total memory size) into SeaBIOS. The SeaBIOS mailing list (seab...@seabios.org) is probably a better location for technical seabios questions. -Kevin -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
