Re: [PATCH 3/4] xen/ppc: Implement early serial printk on pseries

[Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>]

On 6/22/23 3:03 AM, Jan Beulich wrote:
> On 21.06.2023 20:21, Shawn Anastasio wrote:
>> On 6/21/23 12:54 PM, Andrew Cooper wrote:
>>> Given:
>>>
>>> #define r0  0
>>>
>>> do the assemblers really not understand register names?  That seems mad.
>>
>> Yeah as surprising as it is, ppc64 assemblers don't handle register
>> names by default. I think at some point a flag was added to GAS (and
>> probably llvm? will have to check) to define them for you, but I'm not
>> sure which version introduced the flag.
> 
> Isn't it that you simply need to prefix them with %? That looks to be
> working for me without any special options in PPC code I maintain for
> an entirely different purpose.

Yes, this is the approach I'll go with. Originally I wanted to preserve
the non-prefixed syntax, but I discovered that the required flag
(-mregnames) is not supported by llvm.

> Jan

Thanks,
Shawn