Thread (212 messages) 212 messages, 19 authors, 2020-09-10

Re: [PATCH 17/22] arm64: vdso: disable LTO

From: Sami Tolvanen <samitolvanen@google.com>
Date: 2020-06-24 23:40:08
Also in: linux-arch, linux-kbuild, linux-pci, lkml

On Wed, Jun 24, 2020 at 04:05:48PM -0700, Nick Desaulniers wrote:
On Wed, Jun 24, 2020 at 2:52 PM Sami Tolvanen [off-list ref] wrote:
quoted
On Wed, Jun 24, 2020 at 01:58:57PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote:
quoted
On Wed, Jun 24, 2020 at 1:33 PM Sami Tolvanen [off-list ref] wrote:
quoted
Filter out CC_FLAGS_LTO for the vDSO.
Just curious about this patch (and the following one for x86's vdso),
do you happen to recall specifically what the issues with the vdso's
are?
I recall the compiler optimizing away functions at some point, but as
LTO is not really needed in the vDSO, it's just easiest to disable it
there.
Sounds fishy; with extern linkage then I would think it's not safe to
eliminate functions.  Probably unnecessary for the initial
implementation, and something we can follow up on, but always good to
have an answer to the inevitable question "why?" in the commit
message.
Sure. I can test this again with the current toolchain to see if there
are still problems.

Sami

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