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. 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://lore.kernel.org/all/acs2PAZq2k3zjmDW@shlinux89/ > > 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 > >> > >
