[U-Boot] GPT overlap on i.MX6
Lukasz Majewski
lukma at denx.de
Thu Nov 28 09:46:39 UTC 2019
Hi Jagan,
> Hi Lukasz,
>
> On Wed, Nov 27, 2019 at 9:47 PM Lukasz Majewski <lukma at denx.de> wrote:
> >
> > Hi Jagan,
> >
> > > Hi Lukasz,
> > >
> > > On Wed, Nov 27, 2019 at 4:15 PM Lukasz Majewski <lukma at denx.de>
> > > wrote:
> > > >
> > > > Hi Jagan,
> > > >
> > > > > Hi,
> > > > >
> > > > > I have created GPT table start from 8MB for kernel, roots etc.
> > > > > something like
> > > > >
> > > > > Part Start LBA End LBA Name
> > > > > Attributes
> > > > > Type GUID
> > > > > Partition GUID
> > > > > 1 0x00004000 0x00023fff "boota"
> > > > > attrs: 0x0000000000000004
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
> > > > > 2 0x00024000 0x00043fff "bootb"
> > > > > attrs: 0x0000000000000004
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 21686148-6449-6e6f-744e-656564454649
> > > > > 3 0x00044000 0x00243fff "rootfsa"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: b921b045-1df0-41c3-af44-4c6f280d3fae
> > > > > 4 0x00244000 0x00443fff "rootfsb"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 8da63339-0007-60c0-c436-083ac8230908
> > > > > 5 0x00444000 0x0070bfde "data"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 4f72ab70-69be-5948-81ff-4fc3daf24faa
> > > > >
> > > > > I have not included SPL, U-Boot to the partition list since it
> > > > > start from 0x400 in i.MX6. So
> > > > > I'm writing SPL separately using fastboot(with offset) or ums.
> > > > >
> > > > > But by doing this, the partition header seems overlapped so
> > > > > the output looks
> > > > >
> > > > > GUID Partition Table Entry Array CRC is wrong: 0x6a1aba0a !=
> > > > > 0x8e4fd548 find_valid_gpt: *** ERROR: Invalid GPT ***
> > > > > find_valid_gpt: *** Using Backup GPT ***
> > > > > Part Start LBA End LBA Name
> > > > > Attributes
> > > > > Type GUID
> > > > > Partition GUID
> > > > > 1 0x00004000 0x00023fff "boota"
> > > > > attrs: 0x0000000000000004
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
> > > > > 2 0x00024000 0x00043fff "bootb"
> > > > > attrs: 0x0000000000000004
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 21686148-6449-6e6f-744e-656564454649
> > > > > 3 0x00044000 0x00243fff "rootfsa"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: b921b045-1df0-41c3-af44-4c6f280d3fae
> > > > > 4 0x00244000 0x00443fff "rootfsb"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 8da63339-0007-60c0-c436-083ac8230908
> > > > > 5 0x00444000 0x0070bfde "data"
> > > > > attrs: 0x0000000000000000
> > > > > type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> > > > > guid: 4f72ab70-69be-5948-81ff-4fc3daf24faa
> > > > >
> > > > > So, what I understand is If I create the GPT first and then
> > > > > write the SPL, the SPL writing process will destroy the GPT
> > > > > Table and if I write SPL first and then create GPT, the GPT
> > > > > creation process will destroy the SPL.
> > > > >
> > > > > Is there any way to fix this? I remember we can prevent this
> > > > > overlap by preserving GPT Table som other or boot partition
> > > > > instead of having them at the beginning by default.
> > > > >
> > > > > Any inputs?
> > > >
> > > > On the diagram of GPT description [1] there is the info that
> > > > partitions can start from LBA 34 (0x200 * 34) = 0x4400
> > > >
> > > > From the above it seems like you starts from 0x4000 your boota
> > > > partition, which then overwrites the "Entries 5-128" which
> > > > shall be 0 and are protected by CRC written in the Primary GPT
> > > > Header.
> > > >
> > > > Please try to adjust your partition scheme to start from
> > > > 0x4400.
> > >
> > > I still see the overlap. I have created boota at 0x4400 and the
> > > write the SPL at 0x400
> > ^^^^^^ - this overwrites the GPT header IMHO.
>
> True, this overlap GPT. and we don't have an option since ROM
> expecting the SPL at 0x400.
The ROM expects some LBA from eMMC being accessible.
Maybe it would be possible to add some specific for your application
DCD code to enable eMMC's boot{01} partition?
Also IIRC i.MX6 allows playing around with some fuses, so maybe you can
specify eMMC to use boot{01} HW partition?
>
> >
> > You may dump the eMMC and check if this is the case (even with
> > u-boot's md.l utility)
> >
> >
> > I had similar problem on some Beagle Bone Black (AM33x) board.
> >
> > The ROM wanted to boot from the fixed eMMC LBA offset which was
> > clashing with GPT.
> >
> > Fortunately, it was also possible to boot from FAT (it was checked
> > before the raw offset from eMMC case) partition, so I used this
> > option instead.
>
> You mean create FAT partition and copy SPL/U-Boot binaries on the
> directory?
Yes, this worked with BBB.
>
> >
> >
> > But hey, isn't it possible to store SPL/u-boot to the eMMC's boot
> > (the separate HW partition) partition and store GPT to the user
> > accessible one (the large one - e.g. 4 GiB)?
>
> Yes, this is what I'm thinking of. But how to preserve the GPT at
> another partition or user accessible area than beginning (which is
> done by default).
Maybe you can use DCD? Or play around with fuses?
ROM booting options are quite verbose - and I don't believe that NXP
did not consider the use case with GPT and single eMMC as the memory
medium.
(All my boards use SPI-NOR / NOR-FLASH for boot up, and then switch to
eMMC if needed).
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
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