Re: [edk2-devel] [PATCH V2 1/3] MdeModulePkg/PartitionDxe: Put the UDF check ahead of MBR

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

Reviewed-by: Ray Ni <ray.ni@intel.com>

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Gao, Zhichao
> Sent: Wednesday, August 12, 2020 9:21 AM
> 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: [edk2-devel] [PATCH V2 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:
> If the CD/DVD's MBR be handled correctly, it would be enumerated
> as a bootable device with MBR path and FAT filesystem. Some Linux
> Distributions boot from such path (FAT with MBR path for ISO) would
> come into the grub console instead of the installation selection.
> With this change, the CD/DVD would always be enumerated with CD path.
> And it would always boot to the installation selection.
> 
> 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
> 
> 
>