Re: [PATCH 1/4] tools: arm: report an error if the guest RAM is too large

[Julien Grall <julien.grall@linaro.org>]

Hi Ian,

On 04/08/2014 03:19 PM, Ian Campbell wrote:
> Due to the layout of the guest physical address space we cannot support more
> than 768M of RAM before overrunning the area set aside for the grant table. Due
> to the presence of the magic pages at the end of the RAM region guests are
> actually limited to 767M.
> 
> Catch this case during domain build and fail gracefully instead of obscurely
> later on.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
> This is the only patch in this series which I consider to be suitable for
> backporting to Xen 4.4

Sounds good backport this patch. I'm wondering if patch #2 can also be
backported.

> ---
>  tools/libxc/xc_dom_arm.c      |    8 ++++++++
>  xen/include/public/arch-arm.h |    3 ++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> index 3330f12..c085b4a 100644
> --- a/tools/libxc/xc_dom_arm.c
> +++ b/tools/libxc/xc_dom_arm.c
> @@ -262,6 +262,14 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>      const uint64_t modsize = dtb_size + ramdisk_size;
>      const uint64_t ram128mb = rambase + (128<<20);
>  
> +    if ( ramend - 1 > GUEST_RAM_END - NR_MAGIC_PAGES*XC_PAGE_SIZE )

Can you add parenthesis for more readability?

Regards,

-- 
Julien Grall