> On 2023-07-03 17:58:32+0800, Zhangjin Wu wrote:
> > Hi, Thomas
> >
> > >
> > > On 2023-06-29 02:54:35+0800, Zhangjin Wu wrote:
> > > > The crt.h provides a new _start_c() function, which is required by the
> > > > new assembly _start entry of arch-<ARCH>.h (included by arch.h), let's
> > > > include crt.h before arch.h.
> > > >
> > > > This '#include "crt.h"' doesn't let the new _start_c() work immediately,
> > > > but it is a base of the coming patches to move most of the assembly
> > > > _start operations to the _start_c() function for every supported
> > > > architecture.
> > >
> > > Why don't the arch-*.h files include this new header?
> > > They are the users of the new symbol.
> > >
> >
> > I have tried so, but since crt.h itself is not architecture specific, add it
> > before arch.h will avoid every new arch porting add the same thing again and
> > again, currently, we only need to add once. I have even planned to move
> > compiler.h out of arch-*.h, but not yet ;-)
>
> While this saves a few lines of code in my opinion it hurts clarity to
> rely on implicitly pre-included things.
>
To be clearer, what about split the arch.h to sys_arch.h (my_syscall*)
and crt_arch.h? (_start part) and then, we can include crt_arch.h in
crt.h and at the same time, include sys_arch.h in sys.h, and at last
we need to create a <ARCH> directory for the them.
crt.h:
#include "crt_arch.h"
_start_c ()
sys.h:
#include "sys_arch.h"
sys_xxx()
{
my_syscall<N>(...)
}
crt_arch.h:
#ifdef ARCH
#include "<ARCH>/crt_arch.h"
#endif
sys_arch.h:
#ifdef ARCH
#inculde "<ARCH>/sys_arch.h"
#endif
I just found musl uses such structure ;-)
> > every new arch porting
>
> That doesn't seem like a very frequent occurrence :-)
>
Yes, it is not often.
> > And also, crt.h may require more features in the future, like init/fini
> > support, it may be not only used by arch-*.h files.
>
> Do you have a mechanism in mind that supports init/fini without needing
> an ELF parser at runtime? I guess an ELF parser would make it a complete
> no-go.
>
I didn't really think about this yet ;-)
> Also the value added by init/fini seems fairly limited for a statically
> linked (tiny) application.
>
Yeah.
Thanks,
Zhangjin
> > [..]
