Bug 1387361

Summary: Newest 4.8.2-300.fc25.i686 (and also older i686) Fedora 25 kernels have architectural problems with INTEL PAE (32 to 36) HW extentions!
Product: [Fedora] Fedora Reporter: niemand <nobodyless>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED INSUFFICIENT_DATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 25CC: extras-qa, gansalmon, ichavero, itamar, jonathan, kernel-maint, madhu.chinakonda, mchehab, nobodyless
Target Milestone: ---Flags: jforbes: needinfo?
Target Release: ---   
Hardware: i686   
OS: Linux   
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Last Closed: 2017-04-28 17:18:19 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description niemand 2016-10-20 17:08:33 UTC
Description of the problem:
Newest kernel 4.8.2-300.fc25.i686 (and also older i686) Fedora 25 kernels have architectural problems with INTEL PAE (32 to 36) HW extensions!

Version-Release number of selected component (if applicable): kernel 4.8.2-300.fc25.i686-PAE

How reproducible: for ANY INTEL Inside mobile (laptop and notebook) CORE and ATOM CPUs i686 kernel and SOCs having less than/equal 4GB DDR2/DDR3/DDR4 i686 PAE kernel freezes - PAE HW extension kernels. ONLY fulfilled system requirement DDRAM > 4GB memory makes i686 PAE kernels run successfully (on INTEL platforms, have no idea on AMD ones)!

Steps to Reproduce:
1. Install F25 Beta distro (32 bit version) on =< 4GB DDR INTEL platforms;
2. Run -PAE i686 F24/F25 kernel;
3. Platforms hang!!!

Actual results:
Wrong SW Linux kernel INTEL Architecture/implementation for i686 PAE extensions!

Expected results:
PAE i686 kernels to run as NON PAE/normal i686 kernels in the case of DDR =< 2GB. In all other cases, PAE kernels should smartly split DDR on several 4GB segments, to ease TLB physical to virtual user processes's space xlation (to place them on [from minimum 2 to maximum 16] different 4GB physical PAE segments) and on HDD/SSD SWAP Linux space.

Additional info: Please, develop correct IA i686 HW PAE architecture, OK (this what you have/maintain is ad-hock spaghetti approach)?

Thank you,
_nobody_

Comment 1 Laura Abbott 2017-01-17 01:17:22 UTC
*********** MASS BUG UPDATE **************
We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 25 kernel bugs.
 
Fedora 25 has now been rebased to 4.9.3-200.fc25.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.
 
If you have moved on to Fedora 26, and are still experiencing this issue, please change the version to Fedora 26.
 
If you experience different issues, please open a new bug report for those.

Comment 2 niemand 2017-01-27 17:09:56 UTC
Let me continue with architectural woes we all have with x86 (IA32) extended 36 bit architecture (PAE).

Here is what read says: "Architectures that manage their Memory Management Unit (MMU) differently are expected to emulate the three-level page tables. For example, on the x86 without PAE enabled, only two page table levels are available. The Page Middle Directory (PMD) is defined to be of size 1 and “folds back” directly onto the Page Global Directory (PGD) which is optimized out at compile time. Unfortunately, for architectures that do not manage their cache or Translation Lookaside Buffer (TLB) automatically, hooks for machine dependent have to be explicitly left in the code for when the TLB and CPU caches need to be altered and flushed even if they are null operations on some architectures like the x86."

I would like to understand more about the statement: "Unfortunately, for architectures that do not manage their cache or TLB automatically, hooks for machine dependent have to be explicitly left in the code..."???

Do we have x86/IA32 INTEL/AMD specimens, which do NOT manage cache or TLB automatically?

You, Fedora kernel maintainers, tell me, please?!

Thank you,
_nobody_

Comment 3 Justin M. Forbes 2017-04-11 14:45:58 UTC
*********** MASS BUG UPDATE **************

We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 25 kernel bugs.

Fedora 25 has now been rebased to 4.10.9-200.fc25.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.

If you have moved on to Fedora 26, and are still experiencing this issue, please change the version to Fedora 26.

If you experience different issues, please open a new bug report for those.

Comment 4 Justin M. Forbes 2017-04-28 17:18:19 UTC
*********** MASS BUG UPDATE **************
This bug is being closed with INSUFFICIENT_DATA as there has not been a response in 2 weeks. If you are still experiencing this issue, please reopen and attach the 
relevant data from the latest kernel you are running and any data that might have been requested previously.