Re: [Xen-devel] [PATCH] xen/arm64: Make sure we get all debug output

[Dirk Behme <dirk.behme@xxxxxxxxx>]

On 04.02.2016 18:00, Ian Campbell wrote:
> On Thu, 2016-02-04 at 17:49 +0100, Dirk Behme wrote:
> > From: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
> >
> > Starting in the wrong ELx mode I get the following debug output:
> >
> > ...
> > - Current EL 00000004 -
> > - Xen must be entered in NS EL2 mode -
> > - Boot failed -
> >
> > The output of "Please update the bootloader" is missing here.
> >
> > Make sure this is output, too. With this, we get
> >
> > ...
> > - Current EL 00000004 -
> > - Xen must be entered in NS EL2 mode -
> > - Please update the bootloader -
> > - Boot failed -
> >
> > as intended.
> Ah, this is because gas does not concatenate strings in the same way as C,
> i.e. in C:
>         "A" "B" "C"
>
> becomes 'A', 'B', 'C', '\0'
>
> while in gas it becomes 'A', '\0', 'B', '\0', 'C', '\0'
>
> I'd like to modify the "...is missing here" above to go a bit further:
>
>      ...is missing here, because string concatenation in gas, unlike in C,
>      keeps the \0 between each individual string.
>
> Would that be OK with you? (I can do it on commit if you are happy with it)

Sure, fine with me :)

Many thanks!

Dirk

> > Signed-off-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
> > ---
> >   xen/arch/arm/arm64/head.S |    4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> > index 9ed9a93..19fa2bb 100644
> > --- a/xen/arch/arm/arm64/head.S
> > +++ b/xen/arch/arm/arm64/head.S
> > @@ -309,8 +309,8 @@ common_start:
> >           b.eq  el2 /* Yes */
> >
> >           /* OK, we're boned. */
> > -        PRINT("- Xen must be entered in NS EL2 mode -\r\n" \
> > -              "- Please update the bootloader -\r\n")
> > +        PRINT("- Xen must be entered in NS EL2 mode -\r\n")
> > +        PRINT("- Please update the bootloader -\r\n")
> >           b fail
> >
> >   el2:    PRINT("- Xen starting at EL2 -\r\n")

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