The kernel-agnostic 'Trace::timestamp' function for arm_64 executes the
'mrs %0, pmccntr_el0' instruction, which is not permitted for user-level
programs on Linux. This patch shadows the generic timestamp.h header
with dummy that returns zero. This return value prompts the timeout
framework to disable the interpolation of time based on timestamps. This
avoid the illegal-instruction abort but comes with two llimitations:
First, time measurements are effectlively limited to a granulariry of 1
millisecond (deliberately constrained by the timer driver).
The quirk is applied when using the base-linux API. Should a generic
application (that uses the base API only) call 'Trace::timestamp'
directly, the illegal instruction is executed.
Issue #4136
This patch adds support for running Genode/Linux on the AARCH64
architecture.
- The kernel-agnostic startup code (crt0) had to be extended to
capture the initial stack pointer, which the Linux kernel uses
to pass the process environment. This is in line with the
existing startup code for x86_32 and x86_64.
- The link order of the host libraries linked to lx_hybrid
programs had to be adjusted such that libgcc appears at last
because the other libraries depend on symbols provided by
libgcc.
- When using AARCH64 Linux as host, one can execute run scripts
via 'make run/<script> KERNEL=linux BOARD=linux' now.
Issue #4136
By moving core's build-description to a library - a pattern already
employed for the other base platforms - we become able to cleanly split
x86-specific code (I/O-port access) from generic code. This is a
prerequisite for enabling non-x86 architectures such as AARCH64.
Issue #4136
