lkml.org 
[lkml]   [2014]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] arch/x86/xen: Silence compiler warnings
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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-07-11 22:41    [W:0.044 / U:1.908 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site