On Tue, Sep 13, 2016 at 01:15:03PM +0200, Andreas Färber wrote: > Am 13.09.2016 um 11:44 schrieb Jiri Kastner: > > On Tue, Sep 13, 2016 at 07:30:38AM +0200, Matthias Welwarsky wrote: > >> [...] can anyone share some code to switch a PE to Aarch32 mode? > >> I'm on Rpi3, using a custom little program that does nothing but set up > >> the > >> GPIOs and then execute an endless loop. The program runs at EL2 in Aarch64 > >> state. This would certainly speed up work. > > > > rpi3: > > there are aarch64 images available, but at least first images were armv7hl > > (armhfp in debian). i expect u-boot is responsible for switching to > > aarch64. > > because loading kernel8.img using bootcode.bin and start.elf (vc4) starts > > in > > aarch32 (assumption based on fact that first images for rpi3 were aarch32). > > Hm, we have to specify arm_control=0x200 in config.txt for aarch64: > https://build.opensuse.org/package/show/hardware/raspberrypi-firmware
good to know, so with snippets from l-loader we can boot to aarch32 and try to switch to aarch64 and vice versa. > > So I guess bootcode.bin does the switch itself? U-Boot rpi_3 does not > use an arm compiler for any part, only an aarch64. rpi_3_32b is > alternative, not complimentary. > > > hikey: > > during boot, switches from aarch32 to aarch64. not sure, if it is part of > > non-free bootloader (signed??) or hikey edk2. > > l-loader.bin is documented to do that: > https://github.com/96boards/l-loader > thanks for clearing > > jetson tx1: > > userspace part of linux4tegra for jetson tx1 releases are both, armv7hl > > and aarch64, while kernel is compiled for aarch64, so i guess tegra > > downstream kernel has appropriate code for switching from aarch64 to > > aarch32. > > That surely has nothing to do with downstream, any arm64 kernel can run > aarch32 code on hardware that supports it. ThunderX among others does not. tx1 != thunderx. and tx1 does, i just checked it in l4t 23.1 which was only armhfp. what i wanted to point out is where we should look for snippets. how kernel is switching from aa64_el1 to aa32_el0. > > Regards, > Andreas > > -- > SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany > GF: Felix Imendörffer, Jane Smithard, Graham Norton > HRB 21284 (AG Nürnberg)
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