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

[Dirk Behme <dirk.behme@gmail.com>]

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@de.bosch.com>
>>
>> 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@de.bosch.com>
>> ---
>>   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")
>