On Tue, Nov 23, 2021 at 11:33 AM Heiko Stübner <heiko@xxxxxxxxx> wrote: > > Hi Guo, > > Am Dienstag, 23. November 2021, 02:57:14 CET schrieb guoren@xxxxxxxxxx: > > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > > The firmware of riscv (such as opensbi) occupy 2MB(64bit) / > > 4MB(32bit) in Linux. It's very wasteful to small memory footprint > > soc chip such as Allwinner D1s/F133. The kernel parameter gives a > > chance to users to set the proper size of the firmware and get > > more than 1.5MB of memory. > > is this kernel parameter approach a result of the T-Head Ice-SoC > currently loading its openSBI from inside the main u-boot via extfs-load, > directly before the kernel itself [0] ? Looking at the defconfig[1], it may be U-Boot SPL not U-Boot proper. I may be looking at the wrong config though. If U-Boot SPL is actually used, you don't even need to manually load OpenSBI "fw_jump" binary. As Heiko pointed, you should just follow how U-Boot SPL works on hifive unmatched (creating the FIT image) The standard U-Boot SPL uses with fw_dynamic which provides all the flexibility you want. [1] https://github.com/T-head-Semi/u-boot/blob/main/configs/ice_evb_c910_defconfig > > Because that approach in general looks not ideal. > > Normally you want the main u-boot already running with less privileges > so firmware like openSBI should've been already loaded before that. > Even more true when you're employing methods to protect memory regions > from less privileged access. > > A lot of socs set u-boot as opensbi payload, but for the example the D1 > mainline approach uses the Allwinner TOC1 image format to load both > opensbi and the main uboot into memory from its 1st stage loader. > > > Of course the best way would be to just mimic what a number of > arm64 and also riscv socs do and use already existing u-boot utilities. > > U-Boot can create a FIT image containing both main u-boot, dtb and > firmware images that all get loaded from SPL and placed at the correct > addresses before having the SPL jump into opensbi and from there > into u-boot [1] . > > And as Anup was writing, reserved-memory should then be the way > to go to tell the kernel what regions to omit. > > And mainline u-boot has already the means to even take the reserved-memory > from the devicetree used by opensbi and copy it to a new devicetree, > if the second one is different. > > > Heiko > > > [0] https://github.com/T-head-Semi/u-boot/blob/main/include/configs/ice-c910.h#L46 > [1] see spl_invoke_opensbi() in common/spl/spl_opensbi.c > [2] see riscv_board_reserved_mem_fixup() in arch/riscv/lib/fdt_fixup.c > > > > > Guo Ren (3): > > riscv: Remove 2MB offset in the mm layout > > riscv: Add early_param to decrease firmware region > > riscv: Add riscv.fwsz kernel parameter > > > > .../admin-guide/kernel-parameters.txt | 3 +++ > > arch/riscv/include/asm/page.h | 8 +++++++ > > arch/riscv/kernel/head.S | 10 +++----- > > arch/riscv/kernel/vmlinux.lds.S | 5 ++-- > > arch/riscv/mm/init.c | 23 ++++++++++++++++--- > > 5 files changed, 36 insertions(+), 13 deletions(-) > > > > > > > > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-riscv -- Regards, Atish
