Re: [PATCH 2/2] arch: arm: imx: detect secondary boot

[Fabian Pfitzner <f.pfitzner@pengutronix.de>]

On Thu, 2026-05-21 at 12:27 +0000, Sascha Hauer wrote:
> On 2026-05-20 10:33, Fabian Pfitzner wrote:
> > Integrate support to detect secondary boot on imx machines.
> > Copy the logic for detection from the uboot-imx project[1].
> > 
> > The information will be stored in the `bootsource_instance_index`
> > variable.
> > 
> > [1]
> > https://github.com/nxp-imx/uboot-imx/blob/99518e6b6f20cb6a2bf19115e355db9f58100af8/arch/arm/mach-imx/imx8m/soc.c#L792
> > 
> > Signed-off-by: Fabian Pfitzner <f.pfitzner@pengutronix.de>
> > ---
> >  arch/arm/mach-imx/boot.c | 52
> > ++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 52 insertions(+)
> > 
> > diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
> > index
> > 3fea22d05f3bfdf2fe9caa6767e1c7c5ea3ced00..a35a1acc2e71231236d3dd500
> > 8523f6c66912000 100644
> > --- a/arch/arm/mach-imx/boot.c
> > +++ b/arch/arm/mach-imx/boot.c
> > @@ -26,6 +26,8 @@
> >  
> >  #include <soc/fsl/fsl_udc.h>
> >  
> > +int imx8m_detect_secondary_image_boot(void);
> 
> It should be either static without forward declaration or exported
> with
> the declaration in a header file.
> 
> > +
> >  static void
> >  imx_boot_save_loc(void (*get_boot_source)(enum bootsource *, int
> > *))
> >  {
> > @@ -35,6 +37,10 @@ imx_boot_save_loc(void (*get_boot_source)(enum
> > bootsource *, int *))
> >  	get_boot_source(&src, &instance);
> >  
> >  	bootsource_set(src, instance);
> > +
> > +	int index = imx8m_detect_secondary_image_boot();
> 
> You assume you are running on i.MX8M here which is not necessarily
> the
> case.
> 
> > +
> > +	bootsource_set_instance_index(index);
> >  }
> >  
> >  
> > @@ -756,3 +762,49 @@ void imx8mn_get_boot_source(enum bootsource
> > *src, int *instance)
> >  
> >  void imx8mn_boot_save_loc(void)
> >  	__alias(imx8mp_boot_save_loc);
> > +
> > +int imx8m_detect_secondary_image_boot(void)
> > +{
> > +	u32 *rom_log_addr = (u32 *)0x9e0;
> > +	u32 *rom_log;
> > +	u8 event_id;
> > +	int i, boot_secondary = 0;
> > +
> > +	/* If the ROM event log pointer is not valid. */
> > +	if (*rom_log_addr < 0x900000 || *rom_log_addr >= 0xb00000
> > ||
> > +	    *rom_log_addr & 0x3)
> > +		return -EINVAL;
> 
> We have imx8m_get_bootrom_log() which handles different cases like we
> are in PBL/EL3 or in barebox proper. Why not use it here?

I tried using `imx8m_get_bootrom_log()` here, but it does not seem to
work. The function returns an invalid address (0x8000) here.

> 
> I wonder how this works at all because you are derefencing the ROM
> which
> is inside the faulting zero page. I would assume barebox crashes here
> when this is called from barebox proper.
> 
> > +
> > +	/* Parse the ROM event ID version 2 log */
> > +	rom_log = (u32 *)(uintptr_t)(*rom_log_addr);
> > +	for (i = 0; i < 128; i++) {
> > +		event_id = rom_log[i] >> 24;
> 
> We already have defines for this, see arch/arm/mach-imx/bootrom-cmd.c
> 
> Sascha
> 
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-- 
Pengutronix e.K. | Fabian Pfitzner |
Steuerwalder Str. 21 | https://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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