Re: [PATCH v1 1/5] xen/riscv: add stub for share_xen_page_with_guest()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.10.2024 11:15, Oleksii Kurochko wrote:
> To avoid the following linkage fail the stub for share_xen_page_with_guest()
> is introduced:

What do you intend to express with "is introduced"? Is there a problem now?
Would there be a problem with subsequent changes? I'm entirely fine with
adding that stub, but the description should make clear why /when exactly
it's needed.

Jan

>   riscv64-linux-gnu-ld: prelink.o: in function `tasklet_kill':
>   /build/xen/common/tasklet.c:176: undefined reference to 
> `share_xen_page_with_guest'
>   riscv64-linux-gnu-ld: ./.xen-syms.0: hidden symbol 
> `share_xen_page_with_guest' isn't defined
>   riscv64-linux-gnu-ld: final link failed: bad value
> 
> $ find . -name \*.o | while read F; do nm $F | grep share_xen_page_with_guest 
> && echo $F; done
>                  U share_xen_page_with_guest
> ./xen/common/built_in.o
>                  U share_xen_page_with_guest
> ./xen/common/trace.o
>                  U share_xen_page_with_guest
> ./xen/prelink.o
> 
> Despite the linker fingering tasklet.c (very likely a toolchain bug),
> it's trace.o which has the undefined reference.
> 
> Looking at trace.i, there is call of share_xen_page_with_guest() in
> share_xen_page_with_privileged_guests() from asm/mm.h.
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> ---
>  xen/arch/riscv/stubs.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
> index 5951b0ce91..c9a590b225 100644
> --- a/xen/arch/riscv/stubs.c
> +++ b/xen/arch/riscv/stubs.c
> @@ -2,7 +2,9 @@
>  #include <xen/cpumask.h>
>  #include <xen/domain.h>
>  #include <xen/irq.h>
> +#include <xen/mm.h>
>  #include <xen/nodemask.h>
> +#include <xen/sched.h>
>  #include <xen/sections.h>
>  #include <xen/time.h>
>  #include <public/domctl.h>
> @@ -409,3 +411,11 @@ unsigned long get_upper_mfn_bound(void)
>  {
>      BUG_ON("unimplemented");
>  }
> +
> +/* mm.c */
> +
> +void share_xen_page_with_guest(struct page_info *page, struct domain *d,
> +                               enum XENSHARE_flags flags)
> +{
> +    BUG_ON("unimplemented");
> +}