* Re: [edk2-devel] [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec
2021-07-05 9:36 [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec Neal Gompa
@ 2021-07-05 9:59 ` Laszlo Ersek
2021-07-06 1:36 ` Wu, Hao A
2021-07-06 7:36 ` [edk2-devel] " Laszlo Ersek
2 siblings, 0 replies; 4+ messages in thread
From: Laszlo Ersek @ 2021-07-05 9:59 UTC (permalink / raw)
To: devel, ngompa13
Cc: Neal Gompa, Chris Murphy, David Duncan, Hao A Wu, Ray Ni,
Zhichao Gao
On 07/05/21 11:36, Neal Gompa wrote:
> Per UEFI Spec 2.8 (UEFI_Spec_2_8_final.pdf, page 114)
> 5.2.3 Protective MBR
> Table 20. Protective MBR Partition Record protecting the entire disk
>
> The description for BootIndicator states the following:
>
>> Set to 0x00 to indicate a non-bootable partition. If set to any
>> value other than 0x00 the behavior of this flag on non-UEFI
>> systems is undefined. Must be ignored by UEFI implementations.
>
> Unfortunately, we have been incorrectly assuming that the
> BootIndicator value must be 0x00, which leads to problems
> when the 'pmbr_boot' flag is set on a disk containing a GPT
> (such as with GNU parted). When the flag is set, the value
> changes to 0x01, causing this check to fail and the system
> is rendered unbootable despite it being valid from the
> perspective of the UEFI spec.
>
> To resolve this, we drop the check for the BootIndicator
> so that we stop caring about the value set there, which
> restores the capability to boot such disks.
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3474
>
> Cc: Chris Murphy <chrismurphy@fedoraproject.org>
> Cc: David Duncan <davdunc@amazon.com>
> Cc: Lazlo Ersek <lersek@redhat.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Zhichao Gao <zhichao.gao@intel.com>
>
> Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
> ---
> MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> index aefb2d6ecb3f..efaff5e0808f 100644
> --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> @@ -264,8 +264,7 @@ PartitionInstallGptChildHandles (
> // Verify that the Protective MBR is valid
> //
> for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
> - if (ProtectiveMbr->Partition[Index].BootIndicator == 0x00 &&
> - ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
> + if (ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
> UNPACK_UINT32 (ProtectiveMbr->Partition[Index].StartingLBA) == 1
> ) {
> break;
>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Thanks
Laszlo
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec
2021-07-05 9:36 [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec Neal Gompa
2021-07-05 9:59 ` [edk2-devel] " Laszlo Ersek
@ 2021-07-06 1:36 ` Wu, Hao A
2021-07-06 7:36 ` [edk2-devel] " Laszlo Ersek
2 siblings, 0 replies; 4+ messages in thread
From: Wu, Hao A @ 2021-07-06 1:36 UTC (permalink / raw)
To: Neal Gompa, devel@edk2.groups.io
Cc: Chris Murphy, David Duncan, Lazlo Ersek, Ni, Ray, Gao, Zhichao
> -----Original Message-----
> From: Neal Gompa <ngompa@fedoraproject.org>
> Sent: Monday, July 5, 2021 5:36 PM
> To: devel@edk2.groups.io
> Cc: Neal Gompa <ngompa@fedoraproject.org>; Chris Murphy
> <chrismurphy@fedoraproject.org>; David Duncan <davdunc@amazon.com>;
> Lazlo Ersek <lersek@redhat.com>; Wu, Hao A <hao.a.wu@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Gao, Zhichao <zhichao.gao@intel.com>
> Subject: [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator
> per UEFI spec
>
> Per UEFI Spec 2.8 (UEFI_Spec_2_8_final.pdf, page 114)
> 5.2.3 Protective MBR
> Table 20. Protective MBR Partition Record protecting the entire disk
>
> The description for BootIndicator states the following:
>
> > Set to 0x00 to indicate a non-bootable partition. If set to any
> > value other than 0x00 the behavior of this flag on non-UEFI
> > systems is undefined. Must be ignored by UEFI implementations.
>
> Unfortunately, we have been incorrectly assuming that the
> BootIndicator value must be 0x00, which leads to problems
> when the 'pmbr_boot' flag is set on a disk containing a GPT
> (such as with GNU parted). When the flag is set, the value
> changes to 0x01, causing this check to fail and the system
> is rendered unbootable despite it being valid from the
> perspective of the UEFI spec.
>
> To resolve this, we drop the check for the BootIndicator
> so that we stop caring about the value set there, which
> restores the capability to boot such disks.
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3474
>
> Cc: Chris Murphy <chrismurphy@fedoraproject.org>
> Cc: David Duncan <davdunc@amazon.com>
> Cc: Lazlo Ersek <lersek@redhat.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Zhichao Gao <zhichao.gao@intel.com>
>
> Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
> ---
> MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> index aefb2d6ecb3f..efaff5e0808f 100644
> --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> @@ -264,8 +264,7 @@ PartitionInstallGptChildHandles (
> // Verify that the Protective MBR is valid
>
> //
>
> for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
>
> - if (ProtectiveMbr->Partition[Index].BootIndicator == 0x00 &&
>
> - ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION
> &&
>
> + if (ProtectiveMbr->Partition[Index].OSIndicator ==
> PMBR_GPT_PARTITION &&
>
Thanks a lot for the fix.
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
Best Regards,
Hao Wu
> UNPACK_UINT32 (ProtectiveMbr->Partition[Index].StartingLBA) == 1
>
> ) {
>
> break;
>
> --
> 2.31.1
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [edk2-devel] [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec
2021-07-05 9:36 [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec Neal Gompa
2021-07-05 9:59 ` [edk2-devel] " Laszlo Ersek
2021-07-06 1:36 ` Wu, Hao A
@ 2021-07-06 7:36 ` Laszlo Ersek
2 siblings, 0 replies; 4+ messages in thread
From: Laszlo Ersek @ 2021-07-06 7:36 UTC (permalink / raw)
To: devel, ngompa13
Cc: Neal Gompa, Chris Murphy, David Duncan, Hao A Wu, Ray Ni,
Zhichao Gao
On 07/05/21 11:36, Neal Gompa wrote:
> Per UEFI Spec 2.8 (UEFI_Spec_2_8_final.pdf, page 114)
> 5.2.3 Protective MBR
> Table 20. Protective MBR Partition Record protecting the entire disk
>
> The description for BootIndicator states the following:
>
>> Set to 0x00 to indicate a non-bootable partition. If set to any
>> value other than 0x00 the behavior of this flag on non-UEFI
>> systems is undefined. Must be ignored by UEFI implementations.
>
> Unfortunately, we have been incorrectly assuming that the
> BootIndicator value must be 0x00, which leads to problems
> when the 'pmbr_boot' flag is set on a disk containing a GPT
> (such as with GNU parted). When the flag is set, the value
> changes to 0x01, causing this check to fail and the system
> is rendered unbootable despite it being valid from the
> perspective of the UEFI spec.
>
> To resolve this, we drop the check for the BootIndicator
> so that we stop caring about the value set there, which
> restores the capability to boot such disks.
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3474
>
> Cc: Chris Murphy <chrismurphy@fedoraproject.org>
> Cc: David Duncan <davdunc@amazon.com>
> Cc: Lazlo Ersek <lersek@redhat.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Zhichao Gao <zhichao.gao@intel.com>
>
> Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
> ---
> MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> index aefb2d6ecb3f..efaff5e0808f 100644
> --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
> @@ -264,8 +264,7 @@ PartitionInstallGptChildHandles (
> // Verify that the Protective MBR is valid
> //
> for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
> - if (ProtectiveMbr->Partition[Index].BootIndicator == 0x00 &&
> - ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
> + if (ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
> UNPACK_UINT32 (ProtectiveMbr->Partition[Index].StartingLBA) == 1
> ) {
> break;
>
Merged as commit b3db0cb1f8d1, via
<https://github.com/tianocore/edk2/pull/1792>.
I fixed up the authorship meta-datum with "git commit --amend
--author='Neal Gompa <ngompa@fedoraproject.org>'", per BZ comment
<https://bugzilla.tianocore.org/show_bug.cgi?id=3474#c9>.
Thanks
Laszlo
^ permalink raw reply [flat|nested] 4+ messages in thread