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 <[email protected] >: > 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 < > [email protected]>: > >> 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 < >> [email protected]>: >> >>> 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 >>> >>
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