On Fri, 22 Jun 2018, Russell King - ARM Linux wrote: > On Fri, Jun 22, 2018 at 11:57:32AM -0400, Nicolas Pitre wrote: > > That is no longer a kernel config/build issue if you the system > > integrator put an XIP kernel on a target with the wrong DT. > > > > The XIP kernel does require that you provide the actual memory base > > address as a constant to the build system but that could be extracted > > directly from the DT data if having a kconfig prompt for that is too > > unwieldy. The new kconfig macro language in mainline could even be > > leveraged to do that at config time. > > That is actually incorrect - you're too used to the dynamic fixup of > virt_to_phys() and friends now! > > Given that XIP is typically used in environments where the kernel text > is very much unmodifyable, we disable CONFIG_ARM_PATCH_PHYS_VIRT. When > disabled, we use a constant translation, based upon the build-time > CONFIG_PHYS_OFFSET and CONFIG_PAGE_OFFSET settings. > > The early assembler relies upon these settings - which must be known > before we enable the MMU. As such, DT parsing is not available to us > at that point (as we can't run any C code, because we won't be calling > it at the address it was linked for.) I think you got me wrong. I meant DT parsing at config or build time, not at run time. Latest mainline allows kconfig files to call out to external programs now. Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
