Re: [Xen-devel] [PATCH] x86: assert MBI is large enough in pvh-boot.c

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Sep 26, 2018 at 12:05:05PM +0100, Andrew Cooper wrote:
> On 26/09/18 12:00, Wei Liu wrote:
> > The relocation code in __start_xen requires one extra element in the
> > MBI structure. By the looks of it the temporary MBI array is already
> > large enough. Add an assertion to catch any issue in the future.
> >
> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> 
> While this is all well and good, the ASSERT() never actually gets out
> onto the console.  This is because, when a failure occurs, the console
> hasn't been configured yet.
> 
> For development purposes I use:
> 
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index e48039d..64febfa 100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -91,7 +91,7 @@ static uint32_t conringc, conringp;
>  static int __read_mostly sercon_handle = -1;
>  
>  #ifdef CONFIG_X86
> -static bool __read_mostly opt_console_xen; /* console=xen */
> +static bool __read_mostly opt_console_xen = true; /* console=xen */
>  #endif
>  
>  static DEFINE_SPINLOCK(console_lock);
> 
> which gets the details out into the L0 log.
> 
> As an addendum, might it be worth having opt_console_xen be tristate,
> and enabled by the start of the PVH path, so log messages before the
> command line is parsed end up being emitted?

This is fine by me.

Wei.

> 
> ~Andrew

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