Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> writes: > On Tue, 3 Nov 2015, Arnd Bergmann wrote: > >> On Tuesday 03 November 2015 13:32:17 kbuild test robot wrote: >> > >> > net/can/bcm.c: In function 'bcm_proc_show': >> > >> net/can/bcm.c:223:1: warning: the frame size of 1156 bytes is larger than 1024 bytes [-Wframe-larger-than=] >> > } >> >> Interesting, that is a lot of stack for a function that only has a couple >> of local variables: >> >> #define IFNAMSIZ 16 >> char ifname[IFNAMSIZ]; >> struct sock *sk = (struct sock *)m->private; >> struct bcm_sock *bo = bcm_sk(sk); >> struct bcm_op *op; >> >> >> This is a parisc-allyesconfig kernel, so I assume that CONFIG_PROFILE_ALL_BRANCHES >> is on, which instruments every 'if' in the kernel. If that causes problems, >> we could decide to disable the do_div optimization whenever CONFIG_PROFILE_ALL_BRANCHES >> is enabled. > > I have an ARM allyesconfig build here where that function needs a frame > of 88 bytes only. And that is with my do_div optimization applied. > > With the do_div optimization turned off, the stack frame is still 88 > bytes. > > Turning on CONFIG_PROFILE_ALL_BRANCHES makes the frame size to grow to > 96 bytes. > > Keeping CONFIG_PROFILE_ALL_BRANCHES=y and activating the do_div > optimization again, and the function frame size goes back to 88 bytes. > > So I wonder what parisc gcc could be doing with this code. I've seen parisc gcc do many strange things. -- Måns Rullgård mans@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
