A38x: Broken Linux kernel booting over UART
Tom Rini
trini at konsulko.com
Fri Nov 5 15:35:10 CET 2021
On Fri, Nov 05, 2021 at 12:38:21PM +0100, Pali Rohár wrote:
> On Monday 11 October 2021 17:49:05 Pali Rohár wrote:
> > 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...
>
> Hello Tom!
>
> I would like to know, what is required to enable same boot atags
> behavior like before applying that commit 9774462e34fa ("arm: Disable
> ATAGs support")?
>
> I have enabled following U-Boot option (as it seems to be enough):
>
> CONFIG_SUPPORT_PASSING_ATAGS=y
>
> And also I have compiled kernel with following debug options:
>
> CONFIG_DEBUG_LL=y
> CONFIG_DEBUG_MVEBU_UART0_ALTERNATE=y
> CONFIG_DEBUG_UNCOMPRESS=y
>
> (to see early kernel output on mvebu UART console).
>
> But I see only these lines on UART:
>
> Starting kernel ...
>
> DTB:0x014E0798 (0x00004F96)
> C:0x010000E0-0x014E5740->0x010AF400-0x01594A60
> DTB:0x0158FAB8 (0x00004F96)
> Uncompressing Linux... done, booting the kernel.
>
> And no more output. After some time watchdog reboots board.
>
> Which means that something more in U-Boot is needed to enable atags
> booting (with possible appended DTB). Or that mentioned commit really
> broke booting. Any idea?
Looking at the U-Boot commit again, you had previously also been doing
CMDLINE, INITRD and MEMORY ATAGs. Since I see this in the kernel:
/*
* Look for an appended DTB. If found, we cannot use it to
* validate the calculated start of physical memory, as its
* memory nodes may need to be augmented by ATAGS stored at
* an offset from the same start of physical memory.
*/
we might well need to still pass at least the memory tag? No one has
tried (I suspect) a completely empty ATAGs + appended DTB until more or
less now.
--
Tom
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