Re: [Xen-devel] [PATCH]: PVH: specify xen features strings cleany for PVH

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.01.13 at 02:35, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> On Thu, 17 Jan 2013 22:22:47 -0500
> Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> 
>> Jan had some comments about that patch:
>> 
>> https://patchwork.kernel.org/patch/1745041/ 
>> 
>> Please fix it up so I can put it in the Linux tree.
> 
> Please see below.
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> 
> Thanks,
> Mukesh
> 
> 
> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> index 1a6bca1..543877d 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -14,12 +14,17 @@
>  #include <asm/xen/interface.h>
>  
>  #ifdef CONFIG_XEN_X86_PVH
> -#define FEATURES_PVH "|writable_descriptor_tables" \
> -                  "|auto_translated_physmap" \
> -                  "|supervisor_mode_kernel" \
> -                  "|hvm_callback_vector"
> +#define XEN_FEATURES_STR .ascii  "!writable_page_tables"       \
> +                                 "|pae_pgdir_above_4gb"        \
> +                                 "|writable_descriptor_tables" \
> +                                 "|auto_translated_physmap"    \
> +                                 "|supervisor_mode_kernel"     \
> +                                 "|hvm_callback_vector"        \
> +                                 "\0"
>  #else
> -#define FEATURES_PVH /* Not supported */
> +#define XEN_FEATURES_STR .ascii "!writable_page_tables"        \
> +                                "|pae_pgdir_above_4gb"         \
> +                                 "\0"
>  #endif
>  
>       __INIT
> @@ -104,7 +109,7 @@ NEXT_HYPERCALL(arch_6)
>  #endif
>       ELFNOTE(Xen, XEN_ELFNOTE_ENTRY,          _ASM_PTR startup_xen)
>       ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR hypercall_page)
> -     ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .asciz 
> "!writable_page_tables|pae_pgdir_above_4gb"FEATURES_PVH)
> +        ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       XEN_FEATURES_STR)
>       ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE,       .asciz "yes")
>       ELFNOTE(Xen, XEN_ELFNOTE_LOADER,         .asciz "generic")
>       ELFNOTE(Xen, XEN_ELFNOTE_L1_MFN_VALID,

That's not really better. What I'd like you to do is keep the common
part common (i.e. not redundantly defined) and add the PVH-specific
bits (with what amounts to an empty string as the non-PVH
replacement) on top. Meaning you will likely want a mixture of
.ascii and .asciz.

Jan


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