Kernel 5.12 RC (Release Candidate) series

[Doug S]

Kernel 5.12-rc1 has been released. (I'll edit in links when they exist.)

I have been running something very close to 5.12-rc1 for a few hours now, but just compiled:

doug@s18:~$ uname -a
Linux s18 5.12.0-rc1-stock #854 SMP PREEMPT Sun Feb 28 16:38:18 PST 2021 x86_64 x86_64 x86_64 GNU/Linux

Previous cycle threads: 5.11, 5.10, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1, 5.0, 4.20, 4.19 ?, 4.18, 4.17, 4.16, 4.15, 4.14.

See the last few posts on the 5.11 RC series thread for some information on mainline build failures and potential boot issues.

[corradoventu]

https://kernel.ubuntu.com/~kernel-pp...ine/v5.12-rc1/ build failed

[zika]

"Frozen Wasteland"
https://www.phoronix.com/forums/foru...steland-kernel

[zika]

:~$ uname -r5.12.0-051200rc1drmtip20210304-generic

Great thanks to everyone involved.

[Doug S]

Oh for goodness sake, so now they broke the build for everybody.
This kernel config change (old .config is from 5.11):

doug@s18:~/temp-k-git/linux$ scripts/diffconfig .config .config-5.12.0-051200rc1-lowlatency
...
 SURFACE_HOTPLUG n -> m
 SVC_I3C_MASTER n -> m
 SYSTEM_TRUSTED_KEYS "" -> "debian/canonical-certs.pem"
 TCG_TIS_I2C_CR50 n -> m
 USB_CDNS_SUPPORT n -> m

Causes this:

make KERNELRELEASE=5.12.0-rc1-doug ARCH=x86     KBUILD_BUILD_VERSION=857 -f ./Makefile
...
  CALL    scripts/checksyscalls.sh
make[5]: *** No rule to make target 'debian/canonical-certs.pem', needed by 'certs/x509_certificate_list'.  Stop.
make[5]: *** Waiting for unfinished jobs....
...
  CC      kernel/fork.o
make[4]: *** [Makefile:1849: certs] Error 2
make[4]: *** Waiting for unfinished jobs....

So now the compile mainline with stolen Ubuntu mainline kernel configuration procedure becomes (.config starts as copied from 5.12-rc1):

doug@s18:~/temp-k-git/linux$ scripts/config --disable DEBUG_INFO
doug@s18:~/temp-k-git/linux$ scripts/config --set-str SYSTEM_TRUSTED_KEYS ""
doug@s18:~/temp-k-git/linux$ scripts/diffconfig .config-5.12.0-051200rc1-lowlatency .config
 DEBUG_INFO y -> n
 SYSTEM_TRUSTED_KEYS "debian/canonical-certs.pem" -> ""
doug@s18:~/temp-k-git/linux$ time make -j7 olddefconfig bindeb-pkg LOCALVERSION=-doug

My entire compile mainline kernel procedure

[Doug S]

By the way, and just in case anyone is interested, I am using 5.12-rc1 with this change:

doug@s18:~/temp-k-git/linux$ git diff
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 3273360f30f7..3464defa004e 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -636,8 +636,8 @@ static struct cpuidle_state skl_cstates[] __initdata = {
                .enter_s2idle = intel_idle_s2idle, },
        {
                .name = "C1E",
-               .desc = "MWAIT 0x01",
-               .flags = MWAIT2flg(0x01) | CPUIDLE_FLAG_ALWAYS_ENABLE,
+               .desc = "MWAIT 0x03",
+               .flags = MWAIT2flg(0x03) | CPUIDLE_FLAG_ALWAYS_ENABLE,
                .exit_latency = 10,
                .target_residency = 20,
                .enter = &intel_idle,

As a potential solution to an HWP (HardWare Pstate) control problem in Intel processors. It has taken 9 months to figure out. Bug report.

EDIT: the patch is specific to my HWP capable processor, i5-9600K, and needs to be propagated for others.
EDIT 2: I have now entered a downstream bug report, on launchpad.

[zika]

HU:
https://www.phoronix.com/scan.php?pa...c2-Likely-Soon
Disable swapfile as a precaution.

[Doug S]

HU: https://www.phoronix.com/scan.php?pa...1-For-Linux-V3
Disable swapfile as a precaution.

Sorry zika, but I am not following/understanding your caution from that article. Could you expand?

[zika]

Sorry zika, but I am not following/understanding your caution from that article. Could you expand?

Sorry, the mistake is mine, wrong URL. I've edited my mesasge above. Mea culpa. Old fingers and old eyes and bad connection between those...

[Doug S]

Sorry, mistake is mine, wrong URL. I've edited my mesasge above. Mea culpa. Old fingers and old eyes and bad connection between those...

Oh my. Thank you very much for the heads up.

And about the "Old fingers and old eyes and bad connection between those". Ya, me also.

EDIT: By the way, I have never heard of such a caution before. I looked back at every tag in the mainline git tree and there has never been a "dontuse" tag before (or any other odd tag).

EDIT 2: I see that 5.12-rc1 has also been removed from kernel.org