Thanks for the help Jake. I'm trying to automate a process of flipping between actual DOS and EFI. Unfortunately, it sounds like there's no way to get to DOS From EFI so I'll have to work something else out. DOSBox/VM solution won't work for me since I need direct access to the hardware due to the code I'm trying to execute. I appreciate your detailed response.
Thanks again, -Greg On Sun, Jul 22, 2012 at 6:33 PM, Jake Thomas <[email protected]>wrote: > What's wrong with going in and switching the firmware to BIOS mode when > you need to boot into DOS, and then switching it back to EFI mode when > you're done? > > The times when you need DOS to see all your real hardware and/or your real > machine's firmware should be so few and far between, that those rare > switches won't be much of an inconvenience. > > In cases where you don't need DOS to see your real hardware and/or > firmware, simply use DOSBox or run DOS in some other virtual machine. > > If you need DOS to see a real hard drive, you can probably share the hard > drive with DOS through a hypervisor such as QEMU. > > Other hardware sharing options include Xen's PCI passthrough. Though at > this point I'd just switch the firmware mode and boot DOS. > > For something like flashing the BIOS, that can be done from within Linux, > which can be booted from EFI. Certainly DOS games can be ran in DOSBox in > Linux booted from EFI. Low-level DOS hard drive utilities might be able to > work on a hard drive if DOS is running in a hypervisor where the hypervisor > is giving DOS access to the hard drives. The hypervisor itself can be > booted from EFI if it's its own OS (called a baremetal hypervisor), or you > can run a hypervisor in Linux booted from EFI. Either way, the hypervisor > supplies DOS with a BIOS. > > Yes, DOS is one of the few (that I know of) operating systems that never > (or at most rarely, as far as I know) communicates to hardware. Instead, it > asks the processor to run a program to communicate to hardware _for_ it. > These programs are a part of the BIOS specification and are in memory. > Either the chip on the motherboard containing the BIOS has memory addresses > pointing to it to get to the programs, or the programs have been copied to > RAM (called shadow RAM). Therefore DOS really does need a BIOS in its full > glory. > > Jake > > Sent from my iPhone
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