Hi Andrew. Thanks a lot for the guidance!! Rafael R. Machado
Em dom, 13 de ago de 2017 às 15:08, Andrew Fish <af...@apple.com> escreveu: > On Aug 13, 2017, at 6:07 AM, Rafael Machado < > rafaelrodrigues.mach...@gmail.com> wrote: > > Thanks a lot Andrew and Rod. Your comments clarified a lot. > > Just onde last question. > In case of int15/e820 and uefi getMemoryMap. Do you know If this > information os used by the bootloaders? > > > Yes it is, this is how the OS discovers the memory map. > > And do you know the format on these calls outputs? (For the getMemoryMap > the uefi Spec os clear, but didn't find anything about e820). > > > The modern version of 0xE820 is documented in the ACPI Spec owned by your > friendly UEFI Forum. ACPI Spec is here: > http://www.uefi.org/specifications. > > There are some other specs from the 1990's that may be useful for legacy > BIOS. Plug and Play BIOS Specification from 1994, and BIOS Boot > Specification from 1996. For older stuff most people use Ralf Brown's > interrupt list. You kind find all this old BIOS stuff searching the > internwebs. > > Thanks, > > Andrew Fish > > Thanks and Regards > Rafael Machado > > Em sáb, 12 de ago de 2017 00:23, Rod Smith <rodsm...@rodsbooks.com> > escreveu: > > On Aug 11, 2017, at 6:00 AM, Rafael Machado > <rafaelrodrigues.mach...@gmail.com> wrote: > > > Hi everyone > > I have a question that probably some guys here can help. > The scenario I have, is that I need to create a OS image that must be > > able > > to boot at a UEFI system (with no csm module), and at a legacy bios > > system. > > My fist thought is that this is not possible. > > > If I understand you correctly, it most definitely IS possible. Most > major Linux distributions provide installation media that can boot in > either BIOS/CSM/legacy mode or in EFI/UEFI mode. Replicating what those > media do might not be the best way to go, though, since they are also > typically designed to boot when written to optical media or when written > to USB flash drives. To do this, they use a sort of "Frankenstein's > Monster" disk format, so unless you need this cross-media compatibility, > too, using the tools and procedures used to create these installation > media would be overkill and would create something that's overly > complex. These media do illustrate the practicality of what you're > suggesting -- or at least, what I *BELIEVE* you're suggesting. If I've > misinterpreted, please clarify your needs. > > The OS in this case is Linux, and the bootloader is Grub or Syslinux. > > > A single GRUB (or SYSLINUX) binary will not do the job; however, there > are both BIOS and EFI builds of both GRUB and SYSLINUX. The details of > what you'd do would depend on the boot medium (hard disk, USB flash > drive, optical disc, etc.); however, broadly speaking you need to write > both BIOS-mode and EFI-mode versions of your chosen boot loader to the > boot medium, with suitable configuration files in appropriate locations. > > Both GRUB and SYSLINUX are boot loaders that can load a Linux kernel > into memory. The Linux kernel, in turn, does not need to be built for > either BIOS or EFI environments; the same kernel binary will work in > either environment. (One partial exception is that there's a feature > known as the EFI stub loader that turns the Linux kernel into its own > EFI boot loader. If you wanted to use this feature, it would obviously > need to be compiled into the kernel. GRUB does not require this feature, > though, and its presence will not interfere with the kernel being booted > on a BIOS-based computer. Thus, you probably don't need to worry about > it for your purposes. I mention it simply so you don't think it's an > issue if you read something about it elsewhere.) > > -- > Rod Smith > rodsm...@rodsbooks.com > http://www.rodsbooks.com > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel > > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel > > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
