Bug#1116251: linux-image-6.12.48+deb13-rpi: Raspberry Pi Zero W does not boot
Hi Benjmanin,
On Sat, Nov 29, 2025 at 12:02:00AM +0100, Salvatore Bonaccorso wrote:
> Hi Benjamin,
>
> On Fri, Nov 28, 2025 at 10:53:17PM +0100, Benjamin Drung wrote:
> > 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 (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.
> > >
> > > 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 <oreoluwa.babatunde@oss.qualcomm.com>
> > > 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 <oreoluwa.babatunde@oss.qualcomm.com>
> > > Tested-by: William Zhang <william.zhang@broadcom.com>
> > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > > Link: https://lore.kernel.org/r/20250806172421.2748302-1-oreoluwa.babatunde@oss.qualcomm.com
> > > Signed-off-by: Sasha Levin <sashal@kernel.org>
> > >
> > > 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?
>
> I hope it is fine for Uwe that i respond here, he might have another
> more efficient way to reach our goal.
>
> But we have the simple-patching guideline here:
> https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#id-1.6.6.4
>
> That should work within an armel schroot work well, e.g. on a
> porterbox amdahl.d.o i would first setup a schroot via:
>
> schroot -b -c chroot:trixie_armel-dchroot -n linux
> dd-schroot-cmd -c linux apt-get update
> dd-schroot-cmd -c linux apt-get dist-upgrade
> dd-schroot-cmd -c linux apt-get build-dep linux
> schroot -r -c linux
> (see https://dsa.debian.org/doc/schroot/)
>
> Then download the linux/6.12.57-1 source and make the revert patch
> available.
>
> apt-get source linux
> cd linux-*
> ./debian/bin/test-patches -f rpi ../0001-Revert-of-reserved_mem-Restructure-call-site-for-dma.patch
In case you can/want trust unsigned packages (but I have put a
sha256sum along signed with my key in the DD keyring), you can test
the patch revert via the packages on:
https://people.debian.org/~carnil/tmp/linux/1116251/
Regards,
Salvatore
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