Re: [gentoo-user] Re: gcc 7.3 + kernel 4.15 = spectre_v2 fixed

[Alexander Kapshuk <alexander.kapshuk@gmail.com>]

On Mon, Jan 29, 2018 at 7:50 PM, Ian Zimmerman <itz@very.loosely.org> wrote:
> On 2018-01-29 20:11, Adam Carter wrote:
>
>> Comparing the contents of /sys/devices/system/cpu/vulnerabilities/spectre_v2
>>
>> With gcc 7.2 + kernel 4.14.15;
>> Intel system shows; Vulnerable: Minimal generic ASM retpoline
>> AMD system shows: Vulnerable: Minimal AMD ASM retpoline
>>
>> With gcc 7.3 + kernel 4.15.0;
>> Intel system shows; Mitigation: Full generic retpoline
>> AMD system shows' Mitigation: Full AMD retpoline
>
> Is there a simple way, with the upstream (kernel.org) sources, to force
> a compiler different from the system default?  If there is, it's not in the
> README, and a simple grep over the Makefiles also doesn't enlighten.
>
> I am not ready to activate a keyworded gcc for general use.
>
> --
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>

To compile the kernel with a different compiler, the method shown
below may be used, e.g.:
make CC=clang

See [1], for details:
Building the kernel with Clang:
[1] https://lwn.net/Articles/734071/