On Thu, Nov 1, 2018 at 11:32 PM Changbin Du <changbin.du@xxxxxxxxx> wrote: > > On Thu, Nov 01, 2018 at 12:32:48PM +0900, Masahiro Yamada wrote: > > Hi Arnd, > > > > > > On Thu, Nov 1, 2018 at 6:42 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > > > On 10/31/18, Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > > > > On 10/30/18 8:59 PM, Stephen Rothwell wrote: > > > >> Hi all, > > > >> > > > >> Please do not add any v4.21/v5.1 code to your linux-next included trees > > > >> until after the merge window closes. > > > >> > > > >> Changes since 20181030: > > > >> > > > > > > > > > > > > on i386: > > > > > > > > ld: drivers/virt/vboxguest/vboxguest_core.o: in function > > > > `vbg_ioctl_hgcm_call': > > > > vboxguest_core.c:(.text+0x212b): undefined reference to `vbg_hgcm_call32' > > > > > > > > > > > > Full randconfig file is attached. > > > > > > > > Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > > > > > > I ran into the same thing, and lots of others like it; they all go back to > > > the -Og compiler option introduced in commit 94c7dfd01652 ("kernel > > > hacking: support building kernel with -Og optimization level"). > > > > > > > > > I have patches for most of these, but I'd prefer if we could leave > > > that patch out of 4.20 for now, and have it in linux-next for merging > > > into the next merge window, to give us more time to fix up all the > > > regressions. This particular instance is fixed by the patch below. > > > > > > Hmm, I was considering the -Og support for the current MW, > > but it might be better to postpone it for 4.21-rc1... > > > > > > > > > Other symptoms caused by the change are tons of 'section mismatch' > > > warnings for functions that are no longer automatically inlined, and > > > sprintf format string overflow warnings when gcc fails to propagate > > > an upper bound on an integer argument that is printed into a fixed > > > length string. > > > > > > Arnd > > > --- > > > From 8172e650c6797b9cc64c6f7b1c9e5433156290cc Mon Sep 17 00:00:00 2001 > > > From: Arnd Bergmann <arnd@xxxxxxxx> > > > Date: Wed, 31 Oct 2018 16:24:35 +0100 > > > Subject: [PATCH] vbox: fix link error with 'gcc -Og' > > > > > > With the new CONFIG_CC_OPTIMIZE_FOR_DEBUGGING option, we get a link > > > error in the vboxguest driver, when that fails to optimize out the > > > call to the compat handler: > > > > > > drivers/virt/vboxguest/vboxguest_core.o: In function `vbg_ioctl_hgcm_call': > > > vboxguest_core.c:(.text+0x1f6e): undefined reference to `vbg_hgcm_call32' > > > > > > Another compile-time check documents better what we want and avoids > > > the error. > > > > > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > > > > > > diff --git a/drivers/virt/vboxguest/vboxguest_core.c > > > b/drivers/virt/vboxguest/vboxguest_core.c > > > index 3093655c7b92..1475ed5ffcde 100644 > > > --- a/drivers/virt/vboxguest/vboxguest_core.c > > > +++ b/drivers/virt/vboxguest/vboxguest_core.c > > > @@ -1312,7 +1312,7 @@ static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev, > > > return -EINVAL; > > > } > > > > > > - if (f32bit) > > > + if (IS_ENABLED(CONFIG_COMPAT) && f32bit) > > > ret = vbg_hgcm_call32(gdev, client_id, > > > call->function, call->timeout_ms, > > > VBG_IOCTL_HGCM_CALL_PARMS32(call), > > > > Right, but adding the CONFIG_COMPAT guard to both the caller and the callee > > looks a bit redundant... > > > > > > I think most cases causing this kind of problem > > rely on the assumption that 'static' functions are inlined. > > > > We can force the compiler to do so > > by replacing 'static' with 'static __always_inline' > > > Declaring it as normal 'inline' is enough. The inline functions are > still inlined by gcc. Thanks. How about clang? For clang, -Og might be equivalent to -O1 at this moment, but I am not sure. In my understanding, Clang does not inline functions marked with 'static inline' for -Og (or -O1) optimization level. Theoretically, 'inline' keyword is a just hint for the compiler, after all. -- Best Regards Masahiro Yamada