Alrighty, I believe I get it now. GCC preprocessing is used to generate
bitfield files. Then there is a Python utility that translates them to C
code at appropriate points during the build process.
Den mån 13 maj 2019 kl 16:51 skrev Mike Epoch : Thanks a lot for answering. I have to ask a follow-up question. How does the bitfields tool chime in
with the rest of the build process? As an example of why I am asking, here is a build step that I have logged: gcc --sysroot=/home/mb/seL4/build -I../kernel/include
-I../kernel/include/64 -I../kernel/include/arch/riscv
-I../kernel/include/arch/riscv/arch/64 -I../kernel/include/plat/spike
-I../kernel/include/plat/spike/plat/64 -I../kernel/libsel4/include
-I../kernel/libsel4/arch_include/riscv
-I../kernel/libsel4/sel4_arch_include/riscv64
-I../kernel/libsel4/sel4_plat_include/spike
-I../kernel/libsel4/mode_include/64 -Ikernel/gen_config -Ikernel/autoconf
-Ikernel/gen_headers -march=rv64imac -mabi=lp64 -D__KERNEL_64__ -O2 -g
-DNDEBUG -nostdinc -nostdlib -O2 -DHAVE_AUTOCONF -DDEBUG -g -ggdb
-mcmodel=medany -fno-pic -fno-pie -fno-stack-protector
-fno-asynchronous-unwind-tables -std=c99 -Wall -Werror -Wstrict-prototypes
-Wmissing-prototypes -Wnested-externs -Wmissing-declarations -Wundef
-Wpointer-arith -Wno-nonnull -ffreestanding -E -P -MD -MT
kernel/CMakeFiles/kernel_bf_gen_target_1_pbf_temp_lib.dir/kernel_bf_gen_target_1_pbf_temp.c.obj
-MF
kernel/CMakeFiles/kernel_bf_gen_target_1_pbf_temp_lib.dir/kernel_bf_gen_target_1_pbf_temp.c.obj.d
-o
kernel/CMakeFiles/kernel_bf_gen_target_1_pbf_temp_lib.dir/kernel_bf_gen_target_1_pbf_temp.c.obj
-c kernel/kernel_bf_gen_target_1_pbf_temp.c This command line invokes gcc and at its end there is "-c
kernel/kernel_bf_gen_target_1_pbf_temp.c", where the ".c"-file is a
bitfields file. GCC should complain about the file format yet it does not.
How is this achieved? I guess there must be something that presents the
bitfields file in C syntax to GCC. How is this achieved? Regards
Mike Den mån 13 maj 2019 kl 16:42 skrev Mike Epoch <
crypticusername1234@gmail.com>: Thanks a lot for answering. I have to ask a follow-up question. How does the bitfields tool chime in
with the rest of the build process? Here is a build step that I have logged: Den mån 13 maj 2019 kl 15:34 skrev G. Branden Robinson <
g.branden.robinson@gmail.com>: Hi, Mike! At 2019-05-13T14:21:41+0200, Mike Epoch wrote: I am new to this list so please forgive me if this question has been
asked before. No worries; it's a low-traffic list. The seL4 code base contains a slew of files with a file type of "bf".
These files seem to define packed structs that are to fit into words
or d-words. Yes. They're called "bitfields", and you can read more about them here: https://ts.data61.csiro.au/publications/nictaabstracts/Cock_08.abstract.pml Regards,
Branden