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STM32MP157C: How to increase the M4 image size

rhaberkorn
Associate II

‎2025-01-12 11:10 AM - edited ‎2025-01-12 11:24 AM

Hello,

I am running a Linux image based on meta-st-stm32mp (hardknott branch).

I currently have the following in my host device tree:

reserved-memory {
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;

                mcuram2: mcuram2@10000000 {
                        compatible = "shared-dma-pool";
                        reg = <0x10000000 0x40000>;
                        no-map;
                };

                vdev0vring0: vdev0vring0@10040000 {
                        compatible = "shared-dma-pool";
                        reg = <0x10040000 0x1000>;
                        no-map;
                };

                vdev0vring1: vdev0vring1@10041000 {
                        compatible = "shared-dma-pool";
                        reg = <0x10041000 0x1000>;
                        no-map;
                };

                vdev0buffer: vdev0buffer@10042000 {
                        compatible = "shared-dma-pool";
                        reg = <0x10042000 0x4000>;
                        no-map;
                };

                mcuram: mcuram@30000000 {
                        compatible = "shared-dma-pool";
                        reg = <0x30000000 0x40000>;
                        no-map;
                };

                retram: retram@38000000 {
                        compatible = "shared-dma-pool";
                        reg = <0x38000000 0x10000>;
                        no-map;
                };

                gpu_reserved: gpu@d4000000 {
                        reg = <0xd4000000 0x4000000>;
                        no-map;
                };
        };

        mlahb: ahb {
                compatible = "st,mlahb", "simple-bus";
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;
                dma-ranges = <0x00000000 0x38000000 0x10000>,
                             <0x10000000 0x10000000 0x60000>,
                             <0x30000000 0x30000000 0x60000>;

                m4_rproc: m4@10000000 {
                        compatible = "st,stm32mp1-m4";
                        reg = <0x10000000 0x40000>,
                              <0x30000000 0x40000>,
                              <0x38000000 0x10000>;
                        /* ... */
                };
        };

mlahb is from the stm32mp151.dtsi.
Let's say, we'd like to increase the allowed image size to 128kb by changing 0x10000 to 0x20000:

&retram {
	reg = <0x38000000 0x20000>;
};

&mlahb {
	dma-ranges = <0x00000000 0x38000000 0x20000>,
	             <0x10000000 0x10000000 0x60000>,
	             <0x30000000 0x30000000 0x60000>;

	m4_rproc {
		reg = <0x10000000 0x40000>,
		      <0x30000000 0x40000>,
		      <0x38000000 0x20000>;
	};
};

Unfortunately, when trying to load a firmware (echo start > /sys/class/remoteproc/remoteproc0/state),
I still get a kernel crash:

[  376.591779] 8<--- cut here ---
[  376.593848] Unhandled fault: imprecise external abort (0x1c06) at 0x004627a4
[  376.600885] pgd = fc518049
[  376.603571] [004627a4] *pgd=c5ef0835, *pte=00000000, *ppte=00000000
[  376.609836] Internal error: : 1c06 [#1] PREEMPT SMP ARM
[  376.615042] Modules linked in: rpmsg_tty rpmsg_core etnaviv gpu_sched spi_stm32 stm32_rproc sch_fq_codel ipv6
[  376.624955] CPU: 1 PID: 298 Comm: sh Not tainted 5.10.10 #1
[  376.630507] Hardware name: STM32 (Device Tree Support)
[  376.635648] PC is at memcpy+0x54/0x330
[  376.639374] LR is at 0x6263000a
[  376.642499] pc : [<c060d914>]    lr : [<6263000a>]    psr: 20000013
[  376.648753] sp : c5cfbe2c  ip : 2172656c  fp : e0d20000
[  376.653965] r10: 00000000  r9 : 00000000  r8 : 646e6168
[  376.659180] r7 : 206b6361  r6 : 626c6c61  r5 : 63206f4e  r4 : 09007265
[  376.665696] r3 : 6c646e61  r2 : 000011b4  r1 : e0bc9220  r0 : e0d30120
[  376.672213] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[  376.679336] Control: 10c5387d  Table: c5ea006a  DAC: 00000051
[  376.685072] Process sh (pid: 298, stack limit = 0x86cbec92)
[  376.690629] Stack: (0xc5cfbe2c to 0xc5cfc000)
[  376.694979] be20:                            00011354 00011354 00000001 00000000 e0d20000
[  376.703147] be40: e0bb9054 c0a0a584 00011354 10041000 00000000 00000000 00000000 c01175f4
[  376.711314] be60: 00000100 00000000 00000006 00000001 00000020 c34cd800 c5ea7cc0 c121f270
[  376.719482] be80: e0bb9000 c34cd820 c0a06c88 c34cd800 c34cd800 c34cd820 c5ea7cc0 c35c2840
[  376.727649] bea0: 00000000 00000000 00000000 c0be8e54 00000000 c34cd800 c5ea7cc0 c34cd820
[  376.735817] bec0: c35c2840 c0be9380 c34cd800 c34cd9e8 00000000 c34cd9f4 c34cd820 c0a07f78
[  376.743984] bee0: c5ea7cc0 3a12e441 00000cc0 c34cd820 c5ea7a80 00000006 c34cd800 c5ea6610
[  376.752151] bf00: 00000051 c0a097bc 00000006 c5ea6600 c5ea7a80 c5cfbf80 c5ea6610 c03a3c48
[  376.760317] bf20: 00000000 00000000 0000000b c3337c00 00000006 c03a3b50 00534fb0 c5cfbf80
[  376.768484] bf40: c2de3c00 00000004 0052f2f0 c0302348 c316d900 3a12e441 c316d900 00000000
[  376.776650] bf60: c1894900 c3337c00 c3337c00 00000000 00000000 c0100264 c5cfa000 c03026e8
[  376.784816] bf80: 00000000 00000000 c5cfa000 3a12e441 00000003 00000006 00534fb0 b6f6c1e0
[  376.792984] bfa0: 00000004 c0100060 00000006 00534fb0 00000001 00534fb0 00000006 00000000
[  376.801152] bfc0: 00000006 00534fb0 b6f6c1e0 00000004 00000000 bee1b7f0 00534fb0 0052f2f0
[  376.809318] bfe0: 00000004 bee1b7a0 b6e7135f b6dfd386 60000030 00000001 00000000 00000000
[  376.817517] [<c060d914>] (memcpy) from [<c0a0a584>] (rproc_elf_load_segments+0x1a0/0x288)
[  376.825669] [<c0a0a584>] (rproc_elf_load_segments) from [<c0be8e54>] (rproc_start+0x24/0x154)
[  376.834171] [<c0be8e54>] (rproc_start) from [<c0be9380>] (rproc_fw_boot+0x170/0x1a4)
[  376.841898] [<c0be9380>] (rproc_fw_boot) from [<c0a07f78>] (rproc_boot+0x150/0x1a4)
[  376.849541] [<c0a07f78>] (rproc_boot) from [<c0a097bc>] (state_store+0x40/0xc8)
[  376.856841] [<c0a097bc>] (state_store) from [<c03a3c48>] (kernfs_fop_write+0xf8/0x21c)
[  376.864750] [<c03a3c48>] (kernfs_fop_write) from [<c0302348>] (vfs_write+0xc0/0x318)
[  376.872481] [<c0302348>] (vfs_write) from [<c03026e8>] (ksys_write+0x60/0xe4)
[  376.879603] [<c03026e8>] (ksys_write) from [<c0100060>] (ret_fast_syscall+0x0/0x54)
[  376.887237] Exception stack(0xc5cfbfa8 to 0xc5cfbff0)
[  376.892282] bfa0:                   00000006 00534fb0 00000001 00534fb0 00000006 00000000
[  376.900451] bfc0: 00000006 00534fb0 b6f6c1e0 00000004 00000000 bee1b7f0 00534fb0 0052f2f0
[  376.908613] bfe0: 00000004 bee1b7a0 b6e7135f b6dfd386
[  376.913659] Code: f5d1f07c e8b151f8 e2522020 e8a051f8 (aafffffa)
[  376.919737] ---[ end trace e8ef0d82ecc3eec4 ]---
[  376.925593] 8<--- cut here ---
[  376.927384] Unhandled fault: imprecise external abort (0x1c06) at 0x004627a4
[  376.934422] pgd = 6e154e4d
[  376.937107] [004627a4] *pgd=c5c11835, *pte=00000000, *ppte=00000000

This only happens if the actual firmware image has a code+data section larger than 64kb.
Does anybody have any clue what I am missing in the device tree?
I should also try to get a proper backtrace of that crash...

What's the hard limit for M4 firmwares?
In this comment, @PatrickF  said that it's at most 448kb:
https://community.st.com/t5/stm32-mpus-products/possible-advisable-to-increase-the-size-of-m4-coprocessor-text/m-p/51879/highlight/true#M52

What's colliding with the RETRAM section or is it because the M4 core won't execute directly from
RETRAM, but copies code into one of the mcuram regions?
See https://wiki.st.com/stm32mpu/wiki/STM32MP15_MCU_SRAM_internal_memory
Is it the mcuram region that I have to increase?

Yours sincerely,
Robin Haberkorn

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