Re: EFI from usb HDD

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Thu, Jun 10, 2021 at 02:31:46PM +0200, Michal Simek wrote:
> 
> 
> On 6/10/21 12:51 PM, Heinrich Schuchardt wrote:
> > On 6/10/21 12:04 PM, Michal Simek wrote:
> >> Hi,
> >>
> >> On 6/10/21 11:47 AM, Heinrich Schuchardt wrote:
> >>> On 6/10/21 10:44 AM, Michal Simek wrote:
> >>>> Hi,
> >>>>
> >>>> I am playing with booting from USB via EFI. And I see very weird
> >>>> behavior. I have burnt image with grub to USB flashdisk and I have
> >>>> tested it on 3 zynqmp boards. zcu102, zcu104 and SOM Kria board.
> >>>> On zcu102 grub is going to boot menu and everything is working fine as
> >>>> expected.
> >>>> On zcu104 and SOM Kria I am able to get grub not to menu. When I list
> >>>> partitions in grub I see that only SDs are listed:
> >>>> grub> ls
> >>>> (hd0) (hd0,msdos1) (hd1) (hd1,msdos1)
> >>>
> >>> Hello Michal,
> >>>
> >>> thanks for sharing your observations.
> >>>
> >>> What devices do hd0 and hd1 relate to?
> >>>
> >>>>
> >>>> On zcu102(working board) I also see usb(gpt) partitions and SD.
> >>>> grub> ls
> >>>> (hd0) (hd0,gpt2) (hd0,gpt1) (hd1) (hd1,msdos1)
> >>>>
> >>>
> >>> GPT and MBR partitioning are independent of the device type.
> >>>
> >>>>
> >>>> On zcu104 I see one more error message
> >>>> "PE image measurement failed"
> >>>
> >>> This is related to CONFIG_EFI_TCG2_PROTOCOL=y. Do you have a TPMv2? This
> >>> will not stop disk enumeration.
> >>>
> >>>> But I can't see it on SOM.
> >>>>
> >>>> U-Boot image is just the same for all boards. I am using generic
> >>>> xilinx_zynqmp_virt_defconfig.
> >>>>
> >>>> When I compare DT description for USB between zcu102 and zcu104 they
> >>>> are
> >>>> the same. SOM doesn't have usb enabled by default (but I enabled it)
> >>>> but
> >>>> grub starts which means that communication with USB is fine.
> >>>>
> >>>> It is based on my latest patches available here.
> >>>> u-boot/custodians/u-boot-microblaze.git (usb-efi-issue branch)
> >>>>
> >>>> Also when I list usb I see all partitions just fine.
> >>>> ZynqMP> part list usb 0
> >>>>
> >>>> Partition Map for USB device 0  --   Partition Type: EFI
> >>>>
> >>>> Part    Start LBA       End LBA         Name
> >>>>           Attributes
> >>>>           Type GUID
> >>>>           Partition GUID
> >>>>     1     0x00000800      0x001007fe      "Microsoft basic data"
> >>>>           attrs:  0x0000000000000000
> >>>>           type:   ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> >>>>           type:   data
> >>>>           guid:   0e7f8b3d-296b-4720-be9d-c4687d3c4a77
> >>>>     2     0x00100800      0x001197fe      "Microsoft basic data"
> >>>>           attrs:  0x0000000000000000
> >>>>           type:   ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> >>>>           type:   data
> >>>>           guid:   8892eddc-231a-4e6e-a5e1-c310f4482fb7
> >>>>
> >>>>
> >>>> Do you have any idea why on one system is working fine to get to menu
> >>>> and on others there is an issue to get all partitions even u-boot is
> >>>> able to see them and can work with them.
> >>>>
> >>>> Thanks,
> >>>> Michal
> >>>>
> >>>
> >>> Where is the GRUB binary? - If it is in EFI/boot/bootaa64.efi, it could
> >>> be that the USB sub-system is simply not initialized yet when the boot
> >>> manager is called by distroboot.
> >>>
> >>> For testing partition detection in the UEFI sub-system it is enough
> >>> to run
> >>>
> >>>      efidebug devices
> >>>
> >>> Until yesterday we had a problem with partition numbers >= 10, cf.
> >>>
> >>> efi_loader: partition numbers are hexadecimal
> >>> https://source.denx.de/u-boot/u-boot/-/commit/3dca77b1dc1b6dbf9c8b51572fe4b0553cef009f
> >>>
> >>>
> >>>
> >>> Block devices are enumerated in efi_disk_register(). Please, try to add
> >>> debug output there to elucidate the problem.
> >>
> >> I found where the problem is. First of all zcu102 didn't use the same
> >> image as others (it wasn't updated properly).
> >> When you have CONFIG_EFI_CAPSULE_ON_DISK_EARLY that efi_disk_register()
> >> is called before usb block devices are detected and registered that's
> >> why grub doesn't see them.
> > 
> > The problem is CONFIG_EFI_SETUP_EARLY=y required by
> > CONFIG_EFI_CAPSULE_ON_DISK_EARLY.
> > 
> > Why is USB initialized later then MMC?
> 
> It is not just usb. SCSI/sata are behaving in the same way too.
> 
> > 
> > Overall we have a deficiency in the UEFI implementation in that we
> > cannot deal with block devices added or removed after initialization.
> > 
> > Here integration with the driver model is missing.
> 
> Right. And also there are commands which can create MBR partitions and I
> expect when you write image to SD and then run rescan or so you could
> get other partitions too.
> Maybe hook via part_init()? with removing efi_disk_register.

For the record, I have proposed my ideas several times[1], [2].
I'm, however, no longer working on this issue as I have shifted
my focus to UEFI secure boot and capsule update.

-Takahiro Akashi

[1] https://lists.denx.de/pipermail/u-boot/2018-November/347491.html
[2] https://lists.denx.de/pipermail/u-boot/2019-February/357923.html

> > 
> >> I was looking at adding usb start in preboot but preboot is called later.
> >> How this should be solved? Any idea?
> >>
> >> Thanks,
> >> Michal
> >>
> >>
> > +cc Sughosh, Takahiro (who have developed the capsule code)
> 
> Thanks,
> Michal