Re: [Xen-devel] [PATCH 2/4] xen/link: Link .data.schedulers and CONSTRUCTERS in more appropriate locations

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 20/06/2019 09:40, Roger Pau Monné wrote:
> On Wed, Jun 19, 2019 at 09:11:25PM +0100, Andrew Cooper wrote:
>> Neither of these should live in .data
>>
>>  * .data.schedulers is only ever read, so is moved into .rodata
>>  * CONSTRUCTORS is only ever read, and only at boot, so is moved to beside
>>    .init.rodata
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> For x86:
>
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
>
> One comment below:
>
>> ---
>> CC: Jan Beulich <JBeulich@suse.com>
>> CC: Wei Liu <wl@xen.org>
>> CC: Roger Pau Monné <roger.pau@citrix.com>
>> CC: Stefano Stabellini <sstabellini@kernel.org>
>> CC: Julien Grall <julien.grall@arm.com>
>> ---
>>  xen/arch/arm/xen.lds.S | 11 ++++++-----
>>  xen/arch/x86/xen.lds.S | 11 ++++++-----
>>  2 files changed, 12 insertions(+), 10 deletions(-)
>>
>> diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
>> index ec37d38..9fa6c99 100644
>> --- a/xen/arch/x86/xen.lds.S
>> +++ b/xen/arch/x86/xen.lds.S
>> @@ -140,6 +140,11 @@ SECTIONS
>>         *(.data.param)
>>         __param_end = .;
>>  
>> +       . = ALIGN(POINTER_ALIGN);
>> +       __start_schedulers_array = .;
>> +       *(.data.schedulers)
>> +       __end_schedulers_array = .;
>> +
>>  #if defined(CONFIG_HAS_VPCI) && defined(CONFIG_LATE_HWDOM)
>>         . = ALIGN(POINTER_ALIGN);
>>         __start_vpci_array = .;
>> @@ -207,6 +212,7 @@ SECTIONS
>>  
>>         *(.init.rodata)
>>         *(.init.rodata.*)
>> +       CONSTRUCTORS
> According to the ld manual CONSTRUCTORS is only relevant for a.out,
> ECOFF and XCOFF. I'm unsure whether PE does use CONSTRUCTORS or not,
> since it's a descendant of COFF.

CONSTRUCTORS is strictly needed for the GCC coverage build to function
(hence its introduction in the first place), and any code which uses
__attribute__((constructor)) (which we use it in libxc, but not in Xen).

I'd say that the ld manual is out-of-date.

~Andrew

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