Bug#1116251: linux-image-6.12.48+deb13-rpi: Raspberry Pi Zero W does not boot
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 (debian-kernel@lists.debian.org) (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.
--
Benjamin Drung
Debian & Ubuntu Developer
Reply to: