Sergey Bugaev, le mer. 27 mars 2024 19:18:30 +0300, a ecrit:
> It's not always possible to directly access user memory from kernel
> mode. While it's in theory a lot more expensive to fetch each character
> to be printed separately, mach_print() is only a debugging facility, and
> it's not supposed to be used for printing large amounts of data.
Yes, but the atomicity of mach_print is really useful when debugging
issues with several translators etc.
Could you make it use a buffer so we get atomicity for e.g. a hundred
characters?
Samuel
> ---
> kern/syscall_subr.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/kern/syscall_subr.c b/kern/syscall_subr.c
> index e0057d94..0027be29 100644
> --- a/kern/syscall_subr.c
> +++ b/kern/syscall_subr.c
> @@ -43,6 +43,7 @@
> #include <kern/task.h>
> #include <kern/thread.h>
> #include <machine/spl.h> /* for splsched */
> +#include <machine/locore.h> /* for copyin */
>
> #if MACH_FIXPRI
> #include <mach/policy.h>
> @@ -381,6 +382,14 @@ thread_depress_abort(thread_t thread)
> void
> mach_print(const char *s)
> {
> - printf("%s", s);
> + char c;
> + while (TRUE) {
> + if (copyin(s, &c, 1))
> + return;
> + if (c == 0)
> + break;
> + printf("%c", c);
> + s++;
> + }
> }
> #endif /* MACH_KDB */
> --
> 2.44.0
