bugGNU GRUB - Bugs: bug #33445, please add an opportunity to...

 
 

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bug #33445: please add an opportunity to chainload complete files

Submitted by:  Mario 'BitKoenig' Holbe <holbe>
Submitted on:  Tue 31 May 2011 11:37:02 AM UTC  
 
Category: BootingSeverity: Major
Priority: 5 - NormalItem Group: Feature Request
Status: InvalidPrivacy: Public
Assigned to: NoneOriginator Name: 
Open/Closed: ClosedRelease: 
Release: Bazaar - trunkReproducibility: None
Planned Release: None

Thu 23 Jun 2011 06:21:50 PM UTC, comment #1:

Boot protocols are more complicated than "just load the file". You also need details like memory locations or register values. So please file separate feature requests per protocol. Currently we support freedos and ntldr/bootmgr protocols. Also we have a branch for pxe chainloading, so no need to file requests for those. As for UEFI it's a completely different protocol and the issue there is about memory usage.

Vladimir Serbinenko <phcoder>
Project Administrator
Tue 31 May 2011 11:37:02 AM UTC, original submission:

Hello,

It would be great to have an opportunity to chainload complete files. This way grub could, for example, boot PXE loaders.

In my specific case I'm trying to boot a detached DiskCryptor boot loader. DiskCryptor offers two alternatives for detached boot loaders: an ISO image or a PXE image.
The ISO image can be loaded through syslinux memdisk and this works well, but is quite a lot of overhead for just a simple boot loader.
Hence, I tried to chainload the PXE image. This shouldn't be a big issue in general since both, i386 boot sectors as well as i386 PXE loaders expect to be loaded to 0:7C00. Unfortunately chainloading does not work yet, because the current `chainloader' (--force) implementation does only load a single sector. Offering an option to chainload the whole file (--pxe? --whole? --full?) should make this work.

I was able to successfully boot this specific DiskCryptor loader using `ntldr'. I don't know exactly why this works and whether this is intentional or just an accident, because if I got the code right, `ntldr' loads to 2000:7C00. So the reason for this this to work is probably just careful programming of the DiskCryptor loader not to rely on being loaded at segment 0.

An opportunity to chainload complete files could probably also solve bug #31979.

Thanks for your work & regards
Mario

Mario 'BitKoenig' Holbe <holbe>

 

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    Date Changed By Updated Field Previous Value => Replaced By
    Thu 23 Jun 2011 06:21:50 PM UTCphcoderStatusNone=>Invalid
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