Re: [PATCH 0/5] add support for relative references in special sections

From: Ard Biesheuvel
Date: Fri Aug 18 2017 - 02:33:21 EST


On 18 August 2017 at 07:29, Sergey Senozhatsky
<sergey.senozhatsky.work@xxxxxxxxx> wrote:
> Hi Ard,
>
> On (08/18/17 07:12), Ard Biesheuvel wrote:
>> Hi Sergey,
>>
>> Thanks for taking a look
>>
>> On 18 August 2017 at 06:56, Sergey Senozhatsky
>> <sergey.senozhatsky.work@xxxxxxxxx> wrote:
>> > On (08/14/17 11:52), Ard Biesheuvel wrote:
>> >> This adds support for emitting special sections such as initcall arrays,
>> >> PCI fixups and tracepoints as relative references rather than absolute
>> >> references. This reduces the size by 50% on 64-bit architectures, but
>> >> more importantly, it removes the need for carrying relocation metadata
>> >> for these sections in relocatables kernels (e.g., for KASLR) that need
>> >> to fix up these absolute references at boot time. On arm64, this reduces
>> >> the vmlinux footprint of such a reference by 8x (8 byte absolute reference
>> >> + 24 byte RELA entry vs 4 byte relative reference)
>> > [..]
>> >
>> > a side note,
>> > checkpatch complaints quite a lot.
>> >
> [..]
>> I will clean up the meaningful ones in v2, but please don't expect
>> this series to be checkpatch clean: it simply doesn't deal with inline
>> asm very well, and some of this code predates checkpatch by a decade,
>> and I'd rather not mix up rather tricky functional changes with
>> checkpatch cleanup duty.
>
> sure. thanks.
>
> I'm running two x86 boxes with the patch set applied, for
> several days, with no issues being observed. it does save
> some memory (well, several pages in my case) even on "tiny"
> kernels configs.
>

That is good to hear. Thanks.