Re: [PATCH for-4.15 v2] xen: Bump the minimum version of GCC supported to 4.9 for arm32 and 5.1 on arm64

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Julien Grall writes ("[PATCH for-4.15 v2] xen: Bump the minimum version of GCC 
supported to 4.9 for arm32 and 5.1 on arm64"):
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> Compilers older than 4.8 have known codegen issues which can lead to
> silent miscompilation:
> 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
> 
> Furthermore, pre-4.9 GCC have known bugs (including things like
> internal compiler errors on Arm) which would require workaround (I
> haven't checked if we have any in Xen).
> 
> The minimum version of GCC to build the hypervisor on arm is now
> raised to 4.9.
> 
> In addition to that, on arm64, GCC version >= 4.9 and < 5.1 have been
> shown to emit memory references beyond the stack pointer, resulting in
> memory corruption if an interrupt is taken after the stack pointer has
> been adjusted but before the reference has been executed.
> 
> Therefore, the minimum for arm64 is raised to 5.1.
> 
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>