bugGNU GRUB - Bugs: bug #47980, grub2 does not support the legacy...


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bug #47980: grub2 does not support the legacy command "write"

Submitter:  Elmar Stellnberger <estellnb>
Submitted:  Sun 22 May 2016 04:17:34 PM UTC
Category:  Booting Severity:  Major
Priority:  3 - Low Item Group:  Software Error
Status:  None Privacy:  Public
Assigned to:  None Originator Name:  Elmar Stellnberger
Open/Closed:  Open Release:  other
Release:  Reproducibility:  Every Time
Planned Release:  2.03+

Sun 22 May 2016 04:18:18 PM UTC, comment #1: 

  My idea about the write command is that it could serve as a
replacement for kernel parameters whenever an OS needs to be
chainloaded. That way also non-directly supported OSes like Windows or DOS or any new not yet supported ones could be customized.

  The command found for fdubcd.img.gz is:
write --offset=15 /bin/setargs.bat ubcdcmd=keydisk\r\n

It simply replaces the given file for the given string at the given offset. The file itself contains sufficient spaces at the given position in order to hold for the parameter passed via write. As already said there are no additional security/safety considerations necessary as long as the file resides inside a RAM disk.

Elmar Stellnberger <estellnb>
Sun 22 May 2016 04:17:34 PM UTC, original submission:  

Package: grub
   Version: 1:2.02.beta2-6

   I have tried to dd the boot image of the Ultimate Boot CD into a hard disk partition in order to boot it from there. Then I have converted the menu.lst as used by Grub1 on that CD image by grub-menulst2cfg. As it turned out most entries are no more bootable with grub2 because of the 'write' command being no more supported. As Jordan_U has told me on #grub this command would no more be supported due to security reasons.
  However my objection against abandoning support for the write command is that it can happily and safely be used together with ram disks as the Ultimate Boot CD does.
  Anyone here who would mind to implement the write command for Grub2?
I would really believe that Grub2 should be backward compatible!
  Using Grub1 in addition to Grub2 has not proven to be a good
alternative as it can not access iso9660 file systems when booted over a virtual floppy image. Up to now there is also no CD emulation; what works with Grub1 though is to enter the following manually when booting with another old physical grub1-bootcd:

root (hd0,17)
configfile (hd0,17)/boot/grub/menu.lst

Elmar Stellnberger <estellnb>


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  • -email is unavailable- added by phcoder (Updated the item)
  • -email is unavailable- added by estellnb (Submitted the item)

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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-10-11 phcoder Priority5 - Normal 3 - Low
        Planned ReleaseNone 2.03+

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