Kernel 2.4.7: Experimental

The purpose of experimental code drops is early publication of on-going efforts at IBM to allow for

• code review and
• early experiments by "power users".

This page may also be used to "submit" code into the development streams of open source projects.

Warning You may not use experimental patches on a production system or on any system that may get authority over a production system or access to data of a production system. Disregarding this rule may result in severe data loss.

Experimental patches eventually disappear as they will be included in a following release unless proven wrong or replaced by better code.

If you download any software from this web site please be aware of the Warranty Disclaimer and Limitation of Liabilities.

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• z90crypt-2.4.7-s390x-2.tar.gz | MD5 and z90crypt-2.4.7-s390x-2-timer.tar.gz | MD5 (2002-01-21)
  The cryptographic device driver z90crypt for 64-bit is provided for the first time.
  Using z90crypt on 64-bit Kernel 2.4.7 requires the "additional IOCTL translation support" kernel-patch introduced 2002-01-21.
  Documentation for z90crypt is included in the "Linux for zSeries Device Driver and Installation Commands" manual.
  Using z90crypt on VM-guests requires z/VM 4.2 and APAR VM62905.

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• linux-2.4.7-order2-2.tar.gz | MD5 experimental (2001-12-12)

This patch contains a complete replacement for the original (2001-11-09) "order 2 allocation relief" patch. The original patch decreased the kernel stack size to 8KB which turned out to be not enough. As a side-effect of this new patch there is no longer a need for special OCO-modules.

Description:

Order 2 allocation relief.

Symptom:

Under stress and after long uptimes of a 64 bit system the error message "__alloc_pages: 2-order allocation failed." appears and either the fork of a new process fails or an active process dies.

Problem:

The order 2 allocation problem is based in the size of the region and segment tables as defined by the zSeries architecture. A full region or segment table in 64 bit mode takes 16 KB of contiguous real memory. The page allocation routines do not guarantee that a higher order allocation will succeed due to memory fragmentation.

Solution:

The order 2 allocation fix is supposed to reduce the number of order 2 allocations for the region and segment tables to a minimum. To do so it uses a feature of the architecture that allows to create incomplete region and segment tables. In almost all cases a process does not need full region or segment tables. If a full region or segment table is needed it is reallocated to the full size.

Important notices:

• This patch is very S/390 specific and breaks all other architectures.
• This patch does only work for a 64-bit Linux for zSeries kernel and should not be applied if you intend to build a 31-bit kernel.
• This patch is not compatible with the 2001-10-12 (nor the 2001-09-14) "on-demand timer" patch.

To create the complete linux kernel sources, the following patches need to be applied in sequence:

linux-2.4.7.tar.gz (GNU)
+ linux-2.4.7-s390.diff (IBM)
+ linux-2.4.7-s390-1.diff (IBM)
+ linux-2.4.7-s390-2.diff (IBM)
+ linux-2.4.7-s390-3.diff (IBM)
+ linux-2.4.7-s390-4.diff (IBM)
+ linux-2.4.7-order2-2.diff (IBM)

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The following experimental 64-bit OCO modules are required for a 64-bit kernel with the 2001-11-09 patch for "Order 2 allocation relief" applied.

These experimental 64-bit modules are functionally equivalent to the 2001-11-23 recommended modules.

• lcs-2.4.7-s390x-4-order2.tar.gz | MD5 2001-11-23
• qdio-2.4.7-s390x-5-order2.tar.gz | MD5 2001-11-23
• qeth-2.4.7-s390x-5-order2.tar.gz | MD5 2001-11-23

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• linux-2.4.7-order2.tar.gz | MD5 experimental (2001-11-09)

This patch contains the following linux kernel bug fixes:

Description:

Order 2 allocation relief.

Symptom:

Under stress and after long uptimes of a 64 bit system the error message "__alloc_pages: 2-order allocation failed." appears and either the fork of a new process fails or an active process dies.

Problem:

The order 2 allocation problem is based in the size of the region and segment tables as defined by the zSeries architecture. A full region or segment table in 64 bit mode takes 16 KB of contiguous real memory. The page allocation routines do not guarantee that a higher order allocation will succeed due to memory fragmentation.

Solution:

The order 2 allocation fix is supposed to reduce the number of order 2 allocations for the region and segment tables to a minimum. To do so it uses a feature of the architecture that allows to create incomplete region and segment tables. In almost all cases a process does not need full region or segment tables. If a full region or segment table is needed it is reallocated to the full size.

Important notices:

• This patch is very S/390 specific and breaks all other architectures.
• This patch does only work for a 64-bit Linux for zSeries kernel and should not be applied if you intend to build a 31-bit kernel.
• This patch is not compatible with the 2001-10-12 (nor the 2001-09-14) "on-demand timer" patch.
• 64-bit kernels built with this patch applied require special OCO-modules.

To create the complete linux kernel sources, the following patches need to be applied in sequence:
linux-2.4.7.tar.gz (GNU)
+ linux-2.4.7-s390.diff (IBM)
+ linux-2.4.7-s390-1.diff (IBM)
+ linux-2.4.7-s390-2.diff (IBM)
+ linux-2.4.7-s390-3.diff (IBM)
+ linux-2.4.7-order2.diff (IBM)

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The following experimental 64-bit OCO modules are required for a 64-bit kernel with the 2001-11-09 patch for "Order 2 allocation relief" applied.

These experimental 64-bit modules are functionally equivalent to the 2001-11-09 recommended modules.

• lcs-2.4.7-s390x-3-order2.tar.gz | MD5 2001-11-09
• qdio-2.4.7-s390x-4-order2.tar.gz | MD5 2001-11-09
• qeth-2.4.7-s390x-4-order2.tar.gz | MD5 2001-11-09

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• z90crypt-2.4.7-s390-1.tar.gz | MD5 2001-11-09

z90crypt comments & improvements since 2001-09-28 2.4.7 drop.
Bugfixes.

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