On Wed, 6 Nov 2019, Andrii Anisov wrote:
> From: Andrii Anisov <andrii_anisov@xxxxxxxx>
>
> Here several ARM Compiler 6.6 issues are solved or provided a work-around:
>
> - Scatter file is pretty primitive, it has no feature to define symbols
> - ARM linker defined symbols are not counted as referred if only mentioned
> in a steering file for rename or resolve, so a header file is used to
> redefine GNU linker script symbols into armlink defined symbols.
>
> - _srodata type clashes by type with __start_bug_frames so can not be both
> redefined as Load$$_rodata_bug_frames_0$$Base. Use resolve feature of armlink
> steering file.
Why _srodata and __start_bug_frames cannot both be defined as
Load$$_rodata_bug_frames_0$$Base when actually in the case of:
> +#define __per_cpu_data_end Load$$_bss_percpu$$Limit
> +#define __bss_end Load$$_bss_percpu$$Limit
> +#define _end Load$$_bss_percpu$$Limit
They are all defined as "Load$$_bss_percpu$$Limit"? And:
> +#define __init_end Load$$_bss$$Base
> +#define __bss_start Load$$_bss$$Base
They are both defined as "Load$$_bss$$Base"? What's special about
"Load$$_rodata_bug_frames_0$$Base"?
> - C style shift operators are missed among supported scatter file expressions,
> so some needed values are hardcoded in scatter file.
>
> - Rename correspondent ARM Linker defined symbols to those needed by `symbols` tool
> using steering file feature.
>
> - ARM Compiler 6.6 tools are not able to rename sections, so we still need
> GNU toolchain's objcopy for this.
>
> Signed-off-by: Andrii Anisov <andrii_anisov@xxxxxxxx>
> ---
> xen/Rules.mk | 6 +
> xen/arch/arm/Makefile | 24 ++++
> xen/arch/arm/xen.scat.S | 266 ++++++++++++++++++++++++++++++++++++++++++++
I would strongly suggest to rename this file with something not
potentially related to scat
To be honest, I don't think this file should even exist. This looks like a copy of xen.lds.S with a different syntax. Furthermore, the comments from Stefano shows that is going to be hard to maintain/check everything has been written correctly.
So how about trying to abstract xen.lds.S?
> +/*
> + * armlink does not understand shifts in scat file expressions
> + * so hardcode needed values
> + */
Please give a pointer to the doc of the armlink in the commit message. So we can easily cross-check what's happening.
In this case, I don't particularly like the re-definition of the defines outside of their header. This is going to make more difficult if we have to update them in the future.
I can see a few ways to do it:
- Avoid using shifts in the definitions
- Find a way to evaluate the value (maybe similar to asn-offset) before using them.
My preference would be the latter but I could be convinced for the former.
Cheers,
