On Wed, 2025-11-26 at 08:52 +0100, Salvatore Bonaccorso wrote:
> Control: tags -1 + moreinfo
> 
> Hi,
> 
> On Sat, Nov 22, 2025 at 04:27:53PM +0100, Benjamin Drung wrote:
> > Hi Uwe,
> > 
> > On Fri, 2025-11-21 at 09:52 +0100, Uwe Kleine-König wrote:
> > > Hello Benjamin,
> > > 
> > > On Thu, Nov 20, 2025 at 11:11:07AM +0100, Benjamin Drung wrote:
> > > > On Thu, 2025-11-20 at 08:58 +0100, Uwe Kleine-König wrote:
> > > > > On Mon, Nov 17, 2025 at 02:05:41AM +0100, Benjamin Drung wrote:
> > > > > > On Wed, 2025-11-05 at 20:14 +0100, Uwe Kleine-König wrote:
> > > > > > > Can you try adding
> > > > > > > 
> > > > > > >   earlyprintk=serial,0x7e215040
> > > > > > > 
> > > > > > > to the kernel commandline. Not sure this activates the right 
> > > > > > > procedures,
> > > > > > > maybe try it with the working kernel first.
> > > > > > 
> > > > > > I tried with the working kernel 6.12.43+deb13-rpi but these were the
> > > > > > earliest lines:
> > > > > > 
> > > > > > [    4.116565] printk: legacy console [ttyS1] enabled
> > > > > > [    4.129635] printk: legacy bootconsole [earlycon0] disabled
> > > > > > [    4.147050] bcm2835-power bcm2835-power: Broadcom BCM2835 power 
> > > > > > domains driver
> > > > > > [    4.160972] mousedev: PS/2 mouse device common for all mice
> > > > > > [    4.172622] i2c-bcm2835 20805000.i2c: Could not read 
> > > > > > clock-frequency property
> > > > > > [    4.186585] bcm2835-wdt bcm2835-wdt: Broadcom BCM2835 watchdog 
> > > > > > timer
> > > > > > 
> > > > > > I tried with 6.12.57+deb13-rpi but that failed to boot and the
> > > > > > earlyprintk line did not give any additional logs.
> > > > > 
> > > > > Can you please provide a full kernel log of the working kernel?
> > > > 
> > > > dmesg log is attached.
> > > > 
> > > > > Also please provide the output of:
> > > > > 
> > > > >       for f in /proc/tty/driver/*; do echo $f; sed 's/^/  /' < $f; 
> > > > > done
> > > > 
> > > > /proc/tty/driver/serial
> > > >   serinfo:1.0 driver revision:
> > > >   0: uart:unknown port:00000000 irq:0
> > > >   1: uart:16550 mmio:0x20215040 irq:53 tx:15629 rx:0 RTS|CTS|DTR
> > > >   2: uart:unknown port:00000000 irq:0
> > > >   3: uart:unknown port:00000000 irq:0
> > > > /proc/tty/driver/ttyAMA
> > > >   serinfo:1.0 driver revision:
> > > >   0: uart:PL011 rev2 mmio:0x20201000 irq:81 tx:452 rx:980 RTS|CTS|DTR
> > > 
> > > OK, is
> > > 
> > >   earlyprintk=serial,0x20215040
> > > 
> > > more communicative then?
> > 
> > Nope, but I found
> > https://www.raspberrypi.com/documentation/computers/configuration.html#enabling-early-console-for-linux
> > and setting earlycon=uart8250,mmio32,0x20215040 worked. The kernel
> > 6.12.43+deb13-rpi booted with printing the early lines as well (see
> > dmesg of previous mail).
> > 
> > With all other experiments cleaned, I tried the latest kernel:
> > 
> > ```
> > $ cat /etc/default/raspi-extra-cmdline
> > earlycon=uart8250,mmio32,0x20215040
> > $ update-initramfs -u
> > ```
> > 
> > I got following logs before it got stuck:
> > 
> > ```
> > [    0.000000] Booting Linux on physical CPU 0x0
> > [    0.000000] Linux version 6.12.57+deb13-rpi 
> > ([email protected]) (arm-linux-gnueabi-gcc-14 (Debian 
> > 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) #1 Debian 
> > 6.12.57-1 (2025-11-05)
> > [    0.000000] CPU: ARMv6-compatible processor [410fb767] revision 7 
> > (ARMv7), cr=00c5387d
> > [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing 
> > instruction cache
> > [    0.000000] OF: fdt: Machine model: Raspberry Pi Zero W Rev 1.1
> > [    0.000000] random: crng init done
> > [    0.000000] earlycon: uart8250 at MMIO32 0x20215040 (options '')
> > [    0.000000] printk: legacy bootconsole [uart8250] enabled
> > [    0.000000] Memory policy: Data cache writeback
> > [    0.000000] Reserved memory: bypass linux,cma node, using cmdline CMA 
> > params instead
> > [    0.000000] OF: reserved mem: node linux,cma compatible matching fail
> > [    0.000000] cma: Reserved 64 MiB at 0x17000000 on node -1
> > ```
> > 
> > It looks like being cma related and I found a cma boot option in
> > /etc/default/raspi-firmware. So I modified /boot/firmware/cmdline.txt
> > and changed cma=64M to cma=0. Then the system booted without problems:
> > 
> > ```
> > [...]
> > [    0.000000] Reserved memory: bypass linux,cma node, using cmdline CMA 
> > params instead
> > [    0.000000] OF: reserved mem: node linux,cma compatible matching fail
> > [    0.000000] Zone ranges:
> > [    0.000000]   Normal   [mem 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Movable zone start for each node
> > [    0.000000] Early memory node ranges
> > [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Initmem setup node 0 [mem 
> > 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Kernel command line:  dma.dmachans=0x7ff5 
> > bcm2708.boardrev=0x9000c1 bcm2708.serial=0x8bb1238 
> > bcm2708.uart_clock=48000000 bcm2708.disk_led_gpio=47 
> > smsc95xx.macaddr=B8:27:EB:BB:12:38 vc_mem.mem_base=0x1ec00000 
> > vc_mem.mem_size=0x20000000  console=tty0 console=ttyS1,115200 
> > root=/dev/mmcblk0p2 rw fsck.repair=yes net.ifnames=0 cma=0 rootwait 
> > earlycon=uart8250,mmio32,0x20215040
> > [...]
> > ```
> > 
> > Then I persisted this change by setting CMA=0 in
> > /etc/default/raspi-firmware:
> > 
> > ```
> > $ grep -Ev '^(#|$)' /etc/default/raspi-firmware
> > CMA=0
> > $ update-initramfs -u
> > ```
> > 
> > This config removes the cma cmdline option completely. The system still
> > boots:
> > 
> > ```
> > [...]
> > [    0.000000] Memory policy: Data cache writeback
> > [    0.000000] Reserved memory: created CMA memory pool at 0x17000000, size 
> > 64 MiB
> > [    0.000000] OF: reserved mem: initialized node linux,cma, compatible id 
> > shared-dma-pool
> > [    0.000000] OF: reserved mem: 0x17000000..0x1affffff (65536 KiB) map 
> > reusable linux,cma
> > [    0.000000] Zone ranges:
> > [    0.000000]   Normal   [mem 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Movable zone start for each node
> > [    0.000000] Early memory node ranges
> > [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Initmem setup node 0 [mem 
> > 0x0000000000000000-0x000000001bffffff]
> > [    0.000000] Kernel command line:  dma.dmachans=0x7ff5 
> > bcm2708.boardrev=0x9000c1 bcm2708.serial=0x8bb1238 
> > bcm2708.uart_clock=48000000 bcm2708.disk_led_gpio=47 
> > smsc95xx.macaddr=B8:27:EB:BB:12:38 vc_mem.mem_base=0x1ec00000 
> > vc_mem.mem_size=0x20000000  console=tty0 console=ttyS1,115200 
> > root=/dev/mmcblk0p2 rw fsck.repair=yes net.ifnames=0  rootwait 
> > earlycon=uart8250,mmio32,0x20215040
> > [...]
> > ```
> > 
> > That should hopefully narrow down the issue space.
> 
> If I'm not wrong the only cma related change between 6.12.43 and
> 6.12.48 was the backport of 2c223f7239f3 ("of: reserved_mem:
> Restructure call site for dma_contiguous_early_fixup()"):
> 
>       commit 46efab01648a04082266115a8e917c3b26b97fa8
>       Author: Oreoluwa Babatunde <[email protected]>
>       Date:   Wed Aug 6 10:24:21 2025 -0700
> 
>           of: reserved_mem: Restructure call site for 
> dma_contiguous_early_fixup()
> 
>           [ Upstream commit 2c223f7239f376a90d71903ec474ba887cf21d94 ]
> 
>           Restructure the call site for dma_contiguous_early_fixup() to
>           where the reserved_mem nodes are being parsed from the DT so that
>           dma_mmu_remap[] is populated before dma_contiguous_remap() is 
> called.
> 
>           Fixes: 8a6e02d0c00e ("of: reserved_mem: Restructure how the 
> reserved memory regions are processed")
>           Signed-off-by: Oreoluwa Babatunde 
> <[email protected]>
>           Tested-by: William Zhang <[email protected]>
>           Signed-off-by: Marek Szyprowski <[email protected]>
>           Link: 
> https://lore.kernel.org/r/[email protected]
>           Signed-off-by: Sasha Levin <[email protected]>
> 
> Uwe, would that make sense? Benjamin can you try to make a build with
> that commit reverted, does it fix the problem?

Building the kernel on the Pi Zero would probably take ages. I have a
Raspberry Pi 5 running arm64. That should be able to build the kernel in
a armel schroot, shouldn't it? Is there documentation for building the
kernel?

-- 
Benjamin Drung
Debian & Ubuntu Developer

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