Re: [PATCH] AARCH64 add GICv3 system registers

[Marcus Shawcroft <marcus dot shawcroft at arm dot com>]

On 25/09/13 19:48, Andrew Pinski wrote:
> Hi,
>    This patch adds the GICv3 system registers names to the list of
> system register names.  Naveen wrote the patch but I am submitting it.
>
> OK?  Tested for aarch64-linux-gnu with no regressions.
>
> Thanks,
> Andrew Pinski
>
> ChangeLog:
>
> AArch64: Add support for GIC ICC_* system registers in gas
>
> 2013-09-25  Naveen H.S  <Naveen.Hurugalawadi@caviumnetworks.com>
>
> * aarch64-opc.c (aarch64_sys_regs): Add support for GIC ICC_*
> system registers in gas.
>
> PS I will update the date in the changelog before committing it once approved.

These registers are already available via the generic system register 
name syntax.


The system register encoding space has provision for future extensions 
and implementation defined extensions.  This encoding space can already 
be accessed via the generic system register name syntax.

Rather than add extensions to the name space in an adhoc fashion, 
creating dependencies on specific versions of binutils, an alternative 
approach would be to implement a mechanism to define the system register 
name to generic name mapping in a dynamically loaded config file (e.g. 
xml, json etc).  This would avoid creating dependencies on specific 
binutils versions and provide a more convenient mechanism to support 
implementation extensions.

Some comments on the patch presented:

The GIC is optional in the architecture therefore recognition of such 
registers should be tied to a feature being enabled / disabled.

The list of registers included looks incomplete.

Cheers
/Marcus