RE: [PATCH v2 2/3] remoteproc: imx_rproc: Pass bootaddr to SM CPU/LMM reset vector

[Peng Fan]

> Subject: Re: [PATCH v2 2/3] remoteproc: imx_rproc: Pass bootaddr to
> SM CPU/LMM reset vector
> 
> On Thu, Apr 09, 2026 at 08:30:54AM +0800, Peng Fan wrote:
> > On Wed, Apr 08, 2026 at 09:46:32AM -0600, Mathieu Poirier wrote:
> > >On Wed, Apr 08, 2026 at 01:30:16AM +0000, Peng Fan wrote:
> > >> > Subject: Re: [PATCH v2 2/3] remoteproc: imx_rproc: Pass
> bootaddr
> > >> > to SM CPU/LMM reset vector
> > >> >
> > >> [...]
> > >> >
> > >> > >
> > >> > > Aligning the ELF entry point with the hardware reset base on
> > >> > Cortex‑M
> > >> > > systems is possible, but it comes with several risks.
> > >> >
> > >> > I'm not asking to align the ELF entry point with the hardware
> reset base.
> > >> > All I want is to have the correct start address embedded in the
> > >> > ELF file to avoid having to use a mask.
> > >>
> > >> I see, per my understanding:
> > >> FreeRTOS typically exposes __isr_vector, which corresponds to the
> > >> hardware reset / vector table base.
> > >> Zephyr (Cortex‑M) exposes _vector_table, which serves the same
> purpose.
> > >> I am not certain about other RTOSes, but the pattern seems
> consistent:
> > >> the vector table base is already available as a named ELF symbol.
> > >>
> > >> Given that, if the preferred approach is to parse the ELF and
> > >> explicitly retrieve the hardware reset base, I can update the
> implementation accordingly.
> > >> If you prefer to parse the elf file to get the hardware reset base,
> > >> I could update to use them.
> > >>
> > >> Options1: Something as below:
> > >> 1. Include rproc_elf_find_symbol in remoteproc_elf_loader.c 2.
> Use
> > >> below in imx_rproc.c ret = rproc_elf_find_symbol(rproc, fw,
> > >> "__isr_vector", &vector_base); if (ret)
> > >>     ret = rproc_elf_find_symbol(rproc, fw, "__vector_table",
> > >> &vector_base);
> > >>
> > >> if (!ret)
> > >>     rproc->bootaddr = vector_base
> > >> else
> > >>    dev_info(dev, "no __isr_vector or __vector_table\n")
> > >
> > >No
> >
> > If your concern is about rproc->bootaddr, I could introduce
> > imx_rproc->vector_base for i.MX.  Please help detail a bit.
> >
> > >
> > >>
> > >> This makes the hardware reset base explicit, avoids masking
> e_entry.
> > >>
> > >> Option 2: User‑provided reset symbol via sysfs As an alternative,
> > >> we could expose a sysfs attribute, e.g. reset_symbol, allowing
> > >> users to specify the symbol name to be used as the reset base:
> > >>
> > >> echo __isr_vector >
> /sys/class/remoteproc/remoteprocX/reset_symbol
> > >>
> > >
> > >Definitely not.
> > >
> > >The definition of e_entry in the specification is clear, i.e "the
> > >address of the entry point from where the process starts executing".
> > >If masking is required because the tool that puts the image together
> > >gets the wrong address, then it should be fixed.
> >
> > The hardware reset base is the address from which the hardware
> fetches
> > the initial stack pointer and program counter values and loads them
> > into the SP and PC registers.  In contrast, bootaddr (i.e. e_entry)
> > represents the address at which the CPU starts executing code (the
> PC
> > value after reset). As you pointed out earlier, this distinction is clear.
> >
> > In our case, we need to obtain the hardware reset base and pass that
> > value to the system firmware. However, e_entry should not be set to
> > the hardware reset base. Doing so would introduce the issues I
> > described in [1]. This means we should not modify the Zephyr or
> > FreeRTOS build outputs to make e_entry equal to the hardware reset
> base.
> 
> 
> As I said earlier, I am _not_ suggesting to make e_entry equal to the
> hardware reset base.

Let me try to restate my understanding more precisely and please
correct me if I am still missing the point.

From your comment:
"
If masking is required because the tool that puts the image together gets the
wrong address, then it should be fixed.
"

I understand this as saying that masking e_entry is not acceptable, because
e_entry already has a clear and correct meaning: it is the execution entry
address, and the kernel should not reinterpret or “fix up” that value.
At the same time, we still need to provide the hardware reset vector base
to the system firmware, and that value is distinct from e_entry.

On i.MX94/5 platforms the reset base is software‑programmable, but that
information is not represented by e_entry, nor is there currently a
separate place in the remoteproc framework to convey a reset‑vector
base independent of the execution entry point.

Given these constraints, I see limited options on the kernel side. 

One conservative approach would be to rely on a fixed, platform‑defined
reset base for the affected SoCs. And update RTOS linking script to put
the vector to the location of fixed hardware reset base.

Thanks,
Peng

> 
> We are going in circles here.
> 
> >
> > Given these constraints, the feasible solutions I can see are either:
> > - option 1 (explicitly retrieving the hardware reset base), or
> > - continuing to use masking.
> >
> > Please suggest.
> >
> > [1]
> >
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2F
> lore
> > .kernel.org%2Fall%2Facs2PAZq2k3zjmDW%40shlinux89%2F&data=0
> 5%7C02%7Cpen
> >
> g.fan%40nxp.com%7C8a5ce35d492b4adb2d3b08de97192cbb%7C686
> ea1d3bc2b4c6fa
> >
> 92cd99c5c301635%7C0%7C0%7C639114331565834960%7CUnknow
> n%7CTWFpbGZsb3d8e
> >
> yJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsI
> kFOIjoiTWF
> >
> pbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Pnkirz3BMEuLsJU9
> MHQNon84HIyMX
> > 08x1wCK04dS7VU%3D&reserved=0
> >
> > Thanks,
> > Peng
> >
> > >
> > >> The remoteproc core would then resolve that symbol from the ELF
> and
> > >> set rproc->bootaddr accordingly.
> > >> This provides maximum flexibility but does introduce a new
> > >> user‑visible ABI, so I see it more as an opt‑in or fallback
> mechanism.
> > >>
> > >> Please let me know which approach you prefer, and I will update
> > >> this series accordingly in v3..
> > >>
> > >> Thanks,
> > >> Peng.
> > >>
> > >>
> > >> >
> > >> > > 1, Semantic mismatch (ELF vs. hardware behavior) 2,
> Debuggers
> > >> > > may attempt to set breakpoints or start execution at the entry
> > >> > > symbol
> > >> > >