Re: How to get BBS_BBS_DEVICE_PATH from BOOTXXXX variable

[Saqib Khan <saqib.khan2011@gmail.com>]

*BootVariable = mGetVariable(Name, &gEfiGlobalVariableGuid,
&BootVariableSize, NULL);Ptr = (BootVariable+3);         Print(L"
%s",(CHAR16 *)(Ptr));         DevicePath =AllocateZeroPool
(*FilePathListLength)     ;         Ptr+= StrSize((CHAR16 *)Ptr);
 CopyMem (DevicePath, Ptr, *FilePathListLength);*
As Carsey suggested i used the same Math in order to get DevicePath but in
my case it is not working

As documentation this data structure is not aligned so i am assuming that
just after description there should be
FilePathList ,so if i CopyMem * (**FilePathListLength) bytes to DevicePath
i should get the right value but i am getting garbage.

On Thu, Oct 20, 2016 at 1:41 AM, Carsey, Jaben <jaben.carsey@intel.com>
wrote:

> Have you examined the BCFG command in the UEFI Shell?
>
> It does this exact behavior and the code is at: ShellPkg\Library\
> UefiBcfgCommandLib\bcfg.c.
>
> -Jaben
>
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> > Saqib Khan
> > Sent: Wednesday, October 19, 2016 11:18 AM
> > To: Andrew Fish <afish@apple.com>
> > Cc: edk2-devel@ml01.01.org; Laszlo Ersek <lersek@redhat.com>
> > Subject: Re: [edk2] How to get BBS_BBS_DEVICE_PATH from BOOTXXXX
> > variable
> >
> > Hi, so i have parsed the structure as follow :
> >
> >
> >
> >
> >
> >
> >
> > *BootVariable = mGetVariable(Name, &gEfiGlobalVariableGuid,
> > &BootVariableSize, NULL);LDAttr = BootVariable[0];FilePathListLength =
> > (BootVariable+2);Ptr = (BootVariable+3); // for description *
> >
> >
> >
> > *for FilePathList[] Ptr+= StrSize((CHAR16 *)Ptr);         CopyMem (Ptr,
> > DevicePath, *FilePathListLength);*
> >
> >
> > I am able to get LDAttr ,FilePathListLength and description but
> >
> > when i try to check DevicePath->Type it always return 0x01( Hardware
> Device
> > Path) for each device .
> >
> >
> > I have hard drive with legacy OS(BBS_DEVICE_PATH). So it should not
> always
> > return 0x01 .What i am doing wrong in parsing ?
> >
> > Thanks
> >
> > On Tue, Oct 18, 2016 at 11:37 PM, Andrew Fish <afish@apple.com> wrote:
> >
> > >
> > > > On Oct 18, 2016, at 10:40 AM, Laszlo Ersek <lersek@redhat.com>
> wrote:
> > > >
> > > > On 10/18/16 19:18, Saqib Khan wrote:
> > > >> Hi,
> > > >> I can not find structure of BOOTXXXX variable, Can any one help how
> to
> > > >> extract device path from BOOTXXXX variable.
> > > >
> > > > In UEFI-related questions, the UEFI specification has a fair chance
> to
> > > > provide useful information.
> > > >
> > > > Please refer to "3.1.3 Load Options" in the UEFI v2.6 spec, available
> > > > for download from <http://www.uefi.org/specifications>.
> > > >
> > > > Locating the matching structure definition in the edk2 tree is left
> as
> > > > an exercise to the reader ;)
> > > >
> > >
> > > Chapter 3 Boot Manager.
> > >
> > > The structure is EFI_LOAD_OPTION but some of the fields are variable
> > > length so you have to do math to figure stuff out.
> > >
> > > Thanks,
> > >
> > > Andrew Fish
> > >
> > >
> > > > Laszlo
> > > >
> > > > _______________________________________________
> > > > edk2-devel mailing list
> > > > edk2-devel@lists.01.org
> > > > https://lists.01.org/mailman/listinfo/edk2-devel
> > >
> > >
> >
> >
> > --
> > Regards
> > Saqib Ahmed Khanzada
> > _______________________________________________
> > edk2-devel mailing list
> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel
>



-- 
Regards
Saqib Ahmed Khanzada