Didier Spaier
2014-Nov-13 19:12 UTC
[syslinux] Boot fails in a VMware player VM - syslinux 6.03
Hi, On 13/11/2014 19:17, Ady wrote: >> Hi, >> >> On 11/11/2014 02:55, Ady wrote: >> > Again, dd'ing your isohybrid image onto your (virtual or real) drive >> > will fail to boot in EFI mode. Your "syslinux.efi-based" >> > "/isolinux/efiboot.img" will not be capable of booting. This is one >> > of the steps that corresponds to grub2, not to whichever other EFI >> > bootloader you use (e.g. syslinux.efi). >> >> So, it's not possible (yet?) to provide an hybrid ISO image able to >> boot in UEFI and BIOS modes using Syslinux. >> > > That's an inaccurate interpretation. You _can_ build an isohybrid > image with Syslinux 6.03 for both, BIOS and UEFI firmware. Such > image: > > A_ can be burned to optical media, which then can be used to boot > BIOS systems; and, > > B_ can be dd'ed to a (USB) (flash) drive, which then can be used to > boot BIOS systems; and, >o > C_ can be dd'ed to a (USB) (flash) drive, which then can be used to > boot UEFI systems; and, > > D_ can be dd'ed to a (USB) (flash) drive, which then can be used to > boot either/both BIOS systems or UEFI systems. > > E_ can be expanded (I mean, its content) onto a (USB) (flash) drive > with GPT and a FAT ESP (and legacy "MBR"), which then can be used to > boot either/both BIOS systems or UEFI systems. > > The possibility to perform #B/#C/#D/#E (in addition to #A) depends on > the content of the isohybrid image and the parameters used by mkisofs > (or equivalent). One hint: > > -eltorito-alt-boot -no-emul-boot -eltorito-platform 0xEF \ > -eltorito-boot EFI/BOOT/BOOTX64.EFI > > (not "-eltorito-boot isolinux/efiboot.img", which is not used by > Syslinux). > > where BOOTX64.EFI comes from (a.k.a. "is a simple copy of"): > syslinux-6.03/efi64/efi/syslinux.efi. > > I am not going to repeat now all additional requirements (such as > ldlinux.{c32,e64} and that the target system in this example would be > either a BIOS or a UEFI x86_64 one, among other requirements). > > In other words, I was only referring to the limitation of Syslinux in > UEFI mode about being able to boot *optical media*. Expressing this > (current) limitation as "[not] able to boot in UEFI and BIOS modes > using Syslinux" is inaccurate. Thanks Ady, I appreciate your accuracy and stand corrected. However, in my use cases at least (providing installers able to boot in in BIOS _and_ UEFI modes) there's no point in providing _hybrid_ images relying _only_ on Syslinux as they will be usable _only_ for USB booting anyway, in case of UEFI. So if I want to "uniformize" the look of the greeting screens I'll have to provide "USB only" images, not hybrid ones. Or use grub for both BIOS and USB booting, but that's out of scope. Best regards, Didier
> > In other words, I was only referring to the limitation of Syslinux in > > UEFI mode about being able to boot *optical media*. Expressing this > > (current) limitation as "[not] able to boot in UEFI and BIOS modes > > using Syslinux" is inaccurate. > > Thanks Ady, I appreciate your accuracy and stand corrected. > > However, in my use cases at least (providing installers able to boot in > in BIOS _and_ UEFI modes) there's no point in providing _hybrid_ images > relying _only_ on Syslinux as they will be usable _only_ for USB booting > anyway, in case of UEFI. > > So if I want to "uniformize" the look of the greeting screens I'll have > to provide "USB only" images, not hybrid ones. Or use grub for both BIOS > and USB booting, but that's out of scope. > > Best regards, > > Didier > _______________________________________________ > Syslinux mailing list > Submissions to Syslinux at zytor.com > Unsubscribe or set options at: > http://www.zytor.com/mailman/listinfo/syslinux >Indeed... For Syslinux (BIOS and EFI) in the .img file: _ the user understands that it is not for optical media; _ not for optical media, not even in BIOS/CSM; _ if the user needs the media / content to be limited to read-only, it needs some additional method. For Syslinux (BIOS and EFI) in the .iso file: _ the user might assume that the system can boot from optical media not only in BIOS mode but also in UEFI mode (sadly, the latter is currently untrue); _ can be used for optical media in BIOS/CSM; _ can be used from a read-only filesystem, or a writable one. Realistically, less and less users are using optical media, especially on newer computers (which are of course UEFI systems). This means that investing resources in Syslinux development with the specific goal of achieving bootable optical media in UEFI mode is less "productive" than investing resources to achieve other improvements / features. I'm not saying it won't happen - possibly by adding some other, more-important features, then booting optical media in UEFI mode might be also achievable. Regards, Ady.
Didier Spaier
2014-Nov-13 23:17 UTC
[syslinux] Boot fails in a VMware player VM - syslinux 6.03
On 13/11/2014 21:51, Ady wrote: > Realistically, less and less users are using optical media, > especially on newer computers (which are of course UEFI systems). Yes. And if a computer is old enough not to be able to boot off an USB drive, it probably doesn't have an UEFI firmware anyway ;) > This means that investing resources in Syslinux development with the > specific goal of achieving bootable optical media in UEFI mode is > less "productive" than investing resources to achieve other > improvements / features. I'm not saying it won't happen - possibly by > adding some other, more-important features, then booting optical > media in UEFI mode might be also achievable. I can understand that. And fixing the remaining bugs that you've listed in previous posts, so that Syslinux 6.04 can be released and used by default by new versions of Linux distributions, is probably more urgent. Best regards, Didier