Re: [PATCH v2 00/17] xen: support per-cpupool scheduling granularity

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.12.2020 00:53, Andrew Cooper wrote:
> Weirdly, there is a second diagnostic showing up which appears to be
> unrelated and non-fatal, but a concerning non-the-less
> 
> mem_access.c: In function 'p2m_mem_access_check':
> mem_access.c:227:6: note: parameter passing for argument of type 'const
> struct npfec' changed in GCC 9.1
>   227 | bool p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct
> npfec npfec)
>       |      ^~~~~~~~~~~~~~~~~~~~
> 
> It appears to be related to
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88469 and is letting us
> know that the ABI changed.  However, Xen is an embedded project with no
> external linkage, so we can probably compile with -Wno-psabi and be done
> with it.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91710

I have no idea why the fix suggested there hasn't made it into the
code base yet - iirc I had taken it verbatim and it got rid of the
problem in my builds of the compiler.

I don't, btw, think us being "embedded" is an excuse to suppress
the warning. If there really was a code generation difference here
(and not just a false positive warning), an incremental build
across a switch between older and newer gcc would then be broken.

Jan