A38x: Broken Linux kernel booting over UART

Mon Oct 11 17:49:05 CEST 2021

On Monday 11 October 2021 10:45:44 Tom Rini wrote:
> On Mon, Oct 11, 2021 at 04:33:44PM +0200, Pali Rohár wrote:
> > On Monday 11 October 2021 10:32:22 Tom Rini wrote:
> > > On Mon, Oct 11, 2021 at 04:25:48PM +0200, Pali Rohár wrote:
> > > > On Monday 11 October 2021 10:03:21 Tom Rini wrote:
> > > > > On Mon, Oct 11, 2021 at 12:13:29PM +0200, Pali Rohár wrote:
> > > > > 
> > > > > > Hello!
> > > > > > 
> > > > > > Current U-Boot master has broken booting of Linux kernel over UART on
> > > > > > A38x.
> > > > > > 
> > > > > > After transferring image over UART it just prints:
> > > > > > 
> > > > > > CACHE: Misaligned operation at range [01000000, 014e5d96]
> > > > > > ## Total Size      = 0x004e5d96 = 5135766 Bytes
> > > > > > ## Start Addr      = 0x01000000
> > > > > > Kernel image @ 0x1000000 [ 0x000000 - 0x4e0e60 ]
> > > > > > FDT and ATAGS support not compiled in
> > > > > > 
> > > > > > resetting ...
> > > > > > 
> > > > > > It resets board and does not boot kernel. Note that I'm trying to boot
> > > > > > recent 5.15 kernel image, not something old.
> > > > > > 
> > > > > > I did git bisect and it found following commit which broke booting:
> > > > > > 
> > > > > > 9774462e34faaa64a91eb9c68b438a52d22bba6a is the first bad commit
> > > > > > commit 9774462e34faaa64a91eb9c68b438a52d22bba6a
> > > > > > Author: Tom Rini <trini at konsulko.com>
> > > > > > Date:   Mon Aug 30 09:16:30 2021 -0400
> > > > > > 
> > > > > >     arm: Disable ATAGs support
> > > > > > 
> > > > > > Prior this commit booting working fine.
> > > > > > 
> > > > > > Do you have any idea what is with above commit? Or any hints?
> > > > > 
> > > > > Can you provide the full log of what you're doing?  And what's in that
> > > > > image you're passing, exactly?  Thanks.
> > > > 
> > > > Here is full log:
> > > > 
> > > > $ make CROSS_COMPILE=arm-linux-gnueabihf- turris_omnia_defconfig
> > > > ...
> > > > $ make CROSS_COMPILE=arm-linux-gnueabihf- -j8
> > > > ...
> > > > $ ./tools/kwboot -b ./u-boot-spl.kwb -B 5200000 -t /dev/ttyUSB0
> > > > Patching image boot signature to UART
> > > > Injecting binary header code for changing baudrate to 5200000 Bd
> > > > Injecting code for changing baudrate back
> > > > Aligning image header to Xmodem block size
> > > > Sending boot message. Please reboot the target...-
> > > > Waiting 2s and flushing tty
> > > > Sending boot image header (115072 bytes)...
> > > >   0 % [......................................................................]
> > > > ...
> > > >  93 % [...........................................................           ]
> > > > Done
> > > > 
> > > > U-Boot SPL 2021.10-00600-gf331497d3ad4 (Oct 11 2021 - 16:13:39 +0200)
> > > > High speed PHY - Version: 2.0
> > > > MiniPCIe/mSATA card detection... MiniPCIe
> > > > Detected Device ID 6820
> > > > board SerDes lanes topology details:
> > > >  | Lane # | Speed |  Type       |
> > > >  --------------------------------
> > > >  |   0    |   5   | PCIe0       |
> > > >  |   1    |   5   | USB3 HOST0  |
> > > >  |   2    |   5   | PCIe1       |
> > > >  |   3    |   5   | USB3 HOST1  |
> > > >  |   4    |   5   | PCIe2       |
> > > >  |   5    |   0   | SGMII2      |
> > > >  --------------------------------
> > > > High speed PHY - Ended Successfully
> > > > mv_ddr: 14.0.0 
> > > > DDR3 Training Sequence - Switching XBAR Window to FastPath Window
> > > > mv_ddr: completed successfully
> > > > Disabling MCU watchdog... disabled
> > > > Trying to boot from BOOTROM
> > > > Returning to BootROM (return address 0xffff05c4)...
> > > > 
> > > > Changing baudrate to 5200000 Bd
> > > > 
> > > > Sending boot image data (747780 bytes)...
> > > >   0 % [......................................................................]
> > > > ...
> > > >  99 % [.................................                                     ]
> > > > Done
> > > > Finishing transfer
> > > > 
> > > > Changing baudrate back to 115200 Bd
> > > > 
> > > > [Type Ctrl-\ + c to quit]
> > > > 
> > > > 
> > > > U-Boot 2021.10-00600-gf331497d3ad4 (Oct 11 2021 - 16:13:39 +0200)
> > > > 
> > > > SoC:   MV88F6820-A0 at 1600 MHz
> > > > DRAM:  2 GiB (800 MHz, 32-bit, 2T, ECC not enabled)
> > > > WDT:   Started watchdog at 20300 with servicing (60s timeout)
> > > > MMC:   mv_sdh: 0
> > > > Loading Environment from SPIFlash... SF: Detected s25fl164k with page size 256 Bytes, erase size 4 KiB, total 8 MiB
> > > > OK
> > > > Model: Turris Omnia
> > > > Turris Omnia:
> > > >   RAM size: 2048 MiB
> > > >   Serial Number: 0000000B00007B3C
> > > > Regdomain set to **
> > > > Net:   eth0: ethernet at 70000, eth1: ethernet at 30000, eth2: ethernet at 34000
> > > > =>
> > > > 
> > > > $ kermit
> > > > C-Kermit>set line /dev/ttyUSB0
> > > > C-Kermit>set speed 115200
> > > > C-Kermit>set carrier-watch off
> > > > C-Kermit>connect
> > > > Connecting to /dev/ttyUSB0, speed 115200
> > > >  Escape character: Ctrl-\ (ASCII 28, FS): enabled
> > > > Type the escape character followed by C to get back,
> > > > or followed by ? to see other options.
> > > > ----------------------------------------------------
> > > > 
> > > > => echo $uart_boot
> > > > loadb $kernel_addr_r 5200000 && part uuid mmc 0:1 partuuid && setenv bootargs earlyprintk rootwait console=ttyS0,115200 rootfstype=btrfs root=PARTUUID=${partuuid} rootflags=commit=5,subvol=@ rw cfg80211.freg=${regdomain} && bootz ${kernel_addr_r}
> > > > => run uart_boot
> > > > ## Switch baudrate to 5200000 bps and press ENTER ...
> > > > C-Kermit>set speed 5200000
> > > > ?No keywords match - 5200000 (,Transmission rate for /dev/ttyUSB0 (bits per second))
> > > > 
> > > > ?SET SPEED fails, speed is 5260273
> > > > C-Kermit>send /tmp/kernel
> > > > C-Kermit>set speed 115200
> > > > /dev/ttyUSB0, 115200 bps
> > > > C-Kermit>connect
> > > > CACHE: Misaligned operation at range [01000000, 014e5d96]
> > > > ## Total Size     = 0x004e5d96 = 5135766 Bytes
> > > > ## Start Addr      = 0x01000000
> > > > ## Switch baudrate to 115200 bps and press ESC ...
> > > > Kernel image @ 0x1000000 [ 0x000000 - 0x4e0e60 ]
> > > > FDT and ATAGS support not compiled in
> > > > 
> > > > resetting ...
> > > 
> > > OK, and is /tmp/kernel something with an appended dtb then?
> > 
> > Yes, single image suitable for single kermit UART transfer:
> > cat arch/arm/boot/zImage arch/arm/boot/dts/armada-385-turris-omnia.dtb > /tmp/kernel
> 
> Well, OK, there we go.  That's what you need to figure out how to fix
> booting of.  You're hitting the panic in arch/arm/lib/bootm.c and need
> to make sure that (a) we do whatever is needed for appended dtb to be
> found by the kernel still/again and (b) check that ourselves, before
> panic or not, in that case.  Before this was probably enabling ATAGs,
> but that wasn't (I think? I forget the magic behind appended dtb as it's
> been a while) actually used by Linux, just by U-Boot to not panic at
> that point.

Ok, thanks for hints. So seems that som unrelated code path via atags
was used even for DTS booting. I also do not remember details. I will
try to debug it...