[arc64] link 64-bit kernel at high address
vineetgarc opened this issue · 3 comments
So far for debugging/bringup needs we've been linking 64-bit kernel in same address map as 32-bit kernel. Now time is ripe to switch to a 64-bit kernel, linked at high address such as 0xFFFF_0000_0000.
Code: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/tree/arc64-high-link-wip
config
CONFIG_LINUX_LINK_BASE=0xFFFF00000000
CONFIG_LINUX_RAM_BASE=0xFFFF00000000
This currently links with gcc10, but then fails to boot on nSIM fairly early.
Just for update here:
Current arc64 gcc11 is able to link the kernel, but we fail at sched_clock because of foss-for-synopsys-dwc-arc-processors/toolchain#412 (comment)
First version of changes are pushed to https://github.com/foss-for-synopsys-dwc-arc-processors/linux/tree/arc64-high-link-wip .
It can be booted on latest HW and in qemu from https://github.com/foss-for-synopsys-dwc-arc-processors/qemu/tree/arc64-high-addr.
TBD: earlycon is disabled for now, we need to have some early_ioremap in order to use earlycon.
I didn't commit it to arc64 because we need tools support (for example qemu) in order to load vmlinux to correct address.