On 30 January 2018 at 16:02, Michael Fothergill <michael.fothergill@gmail.com> wrote:On 30 January 2018 at 15:23, Elimar Riesebieter <riesebie@lxtec.de> wrote:* rhkramer@gmail.com <rhkramer@gmail.com> [2018-01-29 10:47 -0500]:
[...]
> On the other hand, if I download kernel source, I would need GCC, and a
> version that is sufficient for the code.
One can check the compiler version the running kernel is built with
by:
$ cat /proc/version
Linux version 4.14.15-toy-lxtec-amd64 (riesebie@toy) (gcc version 7.3.0 (Debian 7.3.0-1)) #1 SMP Tue Jan 30 14:20:49 CET 2018That is a very useful command.I ran it myself.
djt /home/mikef/spectre-meltdown-checker # cat /proc/version
Linux version 4.14.14-gentoo (root@djt) (gcc version 7.2.0 (Gentoo 7.2.0-r1)) #1 SMP Tue Jan 23 13:06:23 GMT 2018Here is a bit of the output from the spectre patch checker:
* Mitigation 2
* Kernel compiled with retpoline option: YES
* Kernel compiled with a retpoline-aware compiler: NO (kernel reports minimal retpoline compilation)
* Retpoline enabled: YES
> STATUS: VULNERABLE (Vulnerable: Minimal AMD ASM retpoline)As can be seen here, the compiler I used to create this kernel was not recent enough to make retpoline work.Since I now have gcc 7.3 installed I will do kernel upgrade in a little while and see if I can change the NO in
"* Kernel compiled with a retpoline-aware compiler: NO (kernel reports minimal retpoline compilation)"to YES.....I think it will work.Cheers MFI just ran the kernel rebuild:
djt /home/mikef # cat /proc/version
Linux version 4.14.15-gentoo (root@djt) (gcc version 7.3.0 (Gentoo 7.3.0)) #1 SMP Tue Jan 30 16:22:47 GMT 2018and now the spectre kernel checker says the following:
* Mitigation 2
* Kernel compiled with retpoline option: YES
* Kernel compiled with a retpoline-aware compiler: YES (kernel reports full retpoline compilation)
* Retpoline enabled: YES
> STATUS: NOT VULNERABLE (Mitigation: Full AMD retpoline)New kernels are going to appear soon with fancier fixes for spectre vulnerabilities if I understand it correctly.I can now install them right away; and if I want I can downgrade gentoo testing to gentoo stable and do the very same thing.CheersMF
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Elimar
--
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