Messages in this thread | | | Date | Fri, 11 Jul 2014 16:03:46 -0400 | From | Boris Ostrovsky <> | Subject | Re: [PATCH 2/2] arch/x86/xen: Silence compiler warnings |
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On 07/11/2014 03:54 PM, Daniel Kiper wrote: > Compiler complains in the following way when x86 32-bit kernel > with Xen support is build: > > CC arch/x86/xen/enlighten.o > arch/x86/xen/enlighten.c: In function ‘xen_start_kernel’: > arch/x86/xen/enlighten.c:1726:3: warning: right shift count >= width of type [enabled by default] > > Such line contains following EFI initialization code: > > boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32); > > There is no issue if x86 64-bit kernel is build. However, 32-bit case > generate warning (even if that code will not be executed because Xen > does not work on 32-bit EFI platforms) due to __pa() returning unsigned long > type which has 32-bits width. So move whole EFI initialization stuff > to separate function and build its body conditionally to avoid above > mentioned warning on x86 32-bit architecture. > > Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> > --- > arch/x86/xen/enlighten.c | 35 ++++++++++++++++++++++------------- > 1 file changed, 22 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index bc89647..6abec74 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1516,12 +1516,32 @@ static void __init xen_pvh_early_guest_init(void) > #endif > } > > +static void __init xen_efi_init(void) > +{ > +#ifdef CONFIG_XEN_EFI > + efi_system_table_t *efi_systab_xen; > + > + efi_systab_xen = xen_efi_probe(); > + > + if (efi_systab_xen == NULL) > + return; > + > + strncpy((char *)&boot_params.efi_info.efi_loader_signature, "Xen", > + sizeof(boot_params.efi_info.efi_loader_signature)); > + boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen); > + boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32); > + > + set_bit(EFI_BOOT, &efi.flags); > + set_bit(EFI_PARAVIRT, &efi.flags); > + set_bit(EFI_64BIT, &efi.flags); > +#endif > +} > + > /* First C function to be called on Xen boot */ > asmlinkage __visible void __init xen_start_kernel(void) > { > struct physdev_set_iopl set_iopl; > int rc; > - efi_system_table_t *efi_systab_xen; > > if (!xen_start_info) > return; > @@ -1717,18 +1737,7 @@ asmlinkage __visible void __init xen_start_kernel(void) > > xen_setup_runstate_info(0); > > - efi_systab_xen = xen_efi_probe(); > - > - if (efi_systab_xen) { > - strncpy((char *)&boot_params.efi_info.efi_loader_signature, "Xen", > - sizeof(boot_params.efi_info.efi_loader_signature)); > - boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen); > - boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32); > - > - set_bit(EFI_BOOT, &efi.flags); > - set_bit(EFI_PARAVIRT, &efi.flags); > - set_bit(EFI_64BIT, &efi.flags); > - } > + xen_efi_init();
I'd put ifdef CONFIG_XEN_EFI around the call instead of having it inside the routine.
-boris
> > /* Start the world */ > #ifdef CONFIG_X86_32
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