Messages in this thread | | | Date | Wed, 11 Oct 2006 21:43:01 +0200 | From | Alexander van Heukelum <> | Subject | Re: [PATCH] Remove lilo-loads-only-five-sectors-of-zImage-fixup from setup.S |
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On Wed, Oct 11, 2006 at 11:38:09AM -0700, H. Peter Anvin wrote: > Alexander van Heukelum wrote: > >Hi! > > > >The real-mode kernel (on i386 and x86_64) checks if the bootloader > >loaded it correctly. Apparantly, very old versions of LILO disregarded > >the setupsects field in the bootsector and always just loaded the first > >five sectors. If the kernel is compiled as a zImage, the real-mode > >kernel is able to rectify the situation. At least it was, until the code > >to do so was moved to the eighth sector in order to make space for more > >E820 entries (commit: f9ba70535dc12d9eb57d466a2ecd749e16eca866). This > >occured on 1 May 2005 and as far as I know, noone has complained yet. > >This patch removes the checks for the signature and the fixup code > >completely. > > > >Comments? Which bootloaders are still in use? Kill zImage? > > > > Andrew asked me to comment on this... > > This removes support for boot loaders that did not understand boot > loader protocol version 2.00 or later. This probably includes very > early versions of LILO as well as the long-since obsolete Bootlin and > Shoelace. Those loaders were unable to load bzImages as well. > > I have been urging that we kill zImage for a long time. It is virtually > impossible to build a kernel today that will fit inside the zImage 512K > compressed limitation. > > It would be useful for setup.S to halt with a message if such an early > bootloader is detected, however. This would have to be parked in the > first 2K of the setup area, and can simply be detected by looking for > zero in type_of_loader.
Hi!
The patch should not alter behaviour for any bootloader that takes setupsects into account. It just removes 'support' for bootloaders that have the size of the setup code hardcoded to 4 sectors.
The current version of setup.S already checks if the bootloader understands boot protocol 2.00+ in the case of a big kernel, but that code is also after the 2k-mark. The zero-page still has some unused space between offsets 0x230 and 0x28f. Shall I put/move some code there to check unconditionally if the type_of_loader has been set?
I'll do that if no objections are put forward.
Thanks, Alexander
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