Re: [PATCH 1/3] MdeModulePkg/PartitionDxe: Put the UDF check ahead of MBR

["Ni, Ray" <ray.ni@intel.com>]

> > This would also solve the issue that ISO image with MBR would be treat
> > as MBR device instead of CD/DVD. That would make the behavior of the
> > image boot different.

Can you please explain this in detail?
It's ok to not provide the "root" cause of why the image boot behavior is different.
Saying the specific issue can help people to understand the issue in future.

> -----Original Message-----
> From: Gao, Zhichao <zhichao.gao@intel.com>
> Sent: Tuesday, August 11, 2020 4:34 PM
> To: Ni, Ray <ray.ni@intel.com>; devel@edk2.groups.io
> Cc: Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>;
> Gary Lin <glin@suse.com>; Andrew Fish <afish@apple.com>
> Subject: RE: [PATCH 1/3] MdeModulePkg/PartitionDxe: Put the UDF check
> ahead of MBR
> 
> Ray,
> 
> The MBR info is correct. The order change is to avoid the MBR being checked
> before UDF/ISO 9660 check.
> That is why I make the patch #3 in the last of the patch set.
> 
> Thanks,
> Zhichao
> 
> > -----Original Message-----
> > From: Ni, Ray <ray.ni@intel.com>
> > Sent: Tuesday, August 11, 2020 4:04 PM
> > To: Gao, Zhichao <zhichao.gao@intel.com>; devel@edk2.groups.io
> > Cc: Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>;
> > Gary Lin <glin@suse.com>; Andrew Fish <afish@apple.com>
> > Subject: RE: [PATCH 1/3] MdeModulePkg/PartitionDxe: Put the UDF check
> ahead
> > of MBR
> >
> > Zhichao,
> > Can you also add notes in the commit message describing that for some ISOs
> > (better with more specific ISO info), the MBR information is not correct?
> >
> > Thanks,
> > Ray
> >
> >
> > > -----Original Message-----
> > > From: Gao, Zhichao <zhichao.gao@intel.com>
> > > Sent: Tuesday, August 11, 2020 2:43 PM
> > > To: devel@edk2.groups.io
> > > Cc: Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A
> > > <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>; Gary Lin
> > > <glin@suse.com>; Andrew Fish <afish@apple.com>
> > > Subject: [PATCH 1/3] MdeModulePkg/PartitionDxe: Put the UDF check
> > > ahead of MBR
> > >
> > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2823
> > >
> > > Refer to UEFI spec 2.8, Section 13.3.2, a block device should be
> > > scanned as below order:
> > > 1. GPT
> > > 2. ISO 9660 (El Torito) (UDF should aslo be here) 3. MBR 4. no
> > > partition found
> > > Note: UDF is using the same boot method as CD, so put it in the same
> > > priority with ISO 9660.
> > >
> > > This would also solve the issue that ISO image with MBR would be treat
> > > as MBR device instead of CD/DVD. That would make the behavior of the
> > > image boot different.
> > >
> > > Cc: Jian J Wang <jian.j.wang@intel.com>
> > > Cc: Hao A Wu <hao.a.wu@intel.com>
> > > Cc: Ray Ni <ray.ni@intel.com>
> > > Cc: Gary Lin <glin@suse.com>
> > > Cc: Andrew Fish <afish@apple.com>
> > > Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>
> > > ---
> > >  MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c | 10 +++++++++-
> > >  1 file changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c
> > > b/MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c
> > > index 6a43c3cafb..473e091320 100644
> > > --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c
> > > +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c
> > > @@ -35,11 +35,19 @@ EFI_DRIVER_BINDING_PROTOCOL
> > > gPartitionDriverBinding = {
> > >
> > >  //
> > >  // Prioritized function list to detect partition table.
> > > +// Refer to UEFI Spec 13.3.2 Partition Discovery, the block device //
> > > +should be scanned in below order:
> > > +// 1. GPT
> > > +// 2. ISO 9660 (El Torito) (or UDF)
> > > +// 3. MBR
> > > +// 4. no partiton found
> > > +// Note: UDF is using a same method as booting from CD-ROM, so put it
> > along
> > > +//        with CD-ROM check.
> > >  //
> > >  PARTITION_DETECT_ROUTINE mPartitionDetectRoutineTable[] = {
> > >    PartitionInstallGptChildHandles,
> > > -  PartitionInstallMbrChildHandles,
> > >    PartitionInstallUdfChildHandles,
> > > +  PartitionInstallMbrChildHandles,
> > >    NULL
> > >  };
> > >
> > > --
> > > 2.21.0.windows.1
> >
>