Previously, __internal_syscall() compiled into asm-code that unconditionally
sets the syscall argument registers a0 to a5.
For example, the instruction sequence for a exit syscall looked like
this:
li a0, 1 # in ther caller of exit()
# ... # in newlib:
li a1, 0 # unused arguments
li a2, 0
li a3, 0
li a4, 0
li a5, 0
li a7, 93 # exit syscall number
(i.e. the binary contains then 5 superfluous instructions for this
one argument syscall)
This commit changes the RISC-V syscall code such that only the required
syscall argument registers are set.
GCC detects that argc is known at compile time and thus evaluates all the
if-statements where argc is used at compile time (tested with -O2 and -Os).
The libm gamma functions use the _gamma_signgam field of the reentrant
structure, which changes offset with the --enable-newlib-reent-small
configure option, which means we need to use a newlib nano specific
version of libm in addition to libc in the nano.specs file. Reported
by Keith Packard. There is a riscv-gnu-toolchain patch that goes
along with this to create the new libm_nano.a file.
Signed-off-by: Jim Wilson <jimw@sifive.com>
This patch adds _LITE_EXIT in crt0.S to enable "lite exit" technique in
RISC-V. The changes have been tested in riscv/riscv-gnu-toolchain by
riscv-dejagnu with riscv-sim.exp/riscv-sim-nano.exp.
Upon successful completion, times() shall return the elapsed real time,
in clock ticks, since an arbitrary point in the past (for example,
system start-up time).
Signed-off-by: Kito Cheng <kito.cheng@gmail.com>
Introduce new host configuration variable "have_init_fini" which is set
to "yes" by default. Override it for RISC-V to "no".
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
- For prevent confuse about what BSD license variant we used, 2- or
3-clause license, we change the license to FreeBSD license to make
it unambiguously refers to the 2-clause license.
Georg Sauthoff
Jim Wilson
Denis Ivanov
Sebastian Huber
Chih-Mao Chen
Kito Cheng
Kito Cheng