Red Hat ENTERPRISE LINUX 5.5 - TECHNICAL NOTES Manual page 116

Chapter 1. Package Updates
The set online, set offline, and related rollback and error routines are only processed if the
device is in a FINAL or DISCONNECTED state.
• DASD: Fail requests when device state is less then ready.
A problem was found where in certain device mapper multipath/PPRC setups a DASD device gets
quiesced and then set to the "basic" state to flush its queue and return all already queued requests
back to the device mapper. It was possible that a request was queued after the device's state was
set to basic, and so that request stayed queued, was not processed, and the device mapper was
blocked waiting for it.
This update ensures that all requests that arrive in such a state are returned as failed.
• Set preferred IBM S/390 console based on conmode.
A problem was found where if conmode was set to 3270 to enable the 3270 terminal device driver,
kernel console messages were not displayed in the console view. This is because the default
preferred console is set to "ttyS". For the 3270 terminal device driver, the preferred console must be
set to "tty3270".
This update introduces a new function to set the preferred console based on the specified conmode.
• Optimize storage key operations for anonymous pages.
A problem was found where removal of anonymous mappings resulted in poor performance. This
update optimizes the instructions that are used for these operations.
• CIO: set correct number of internal I/O retries.
A problem was found where if a device has n paths and that device is not path-grouped, and an
internal I/O command fails, then the control unit presents the error sense n times on each different
path. Because CIO only performs five retries, devices with five or more paths run out of retries
before their functional status can be correctly determined.
This update increases the number of retries to 10 to prevent this problem from occurring.
• Add module signing to IBM S/390 kernels.
• Make CIO_* macros safe if dbfs are not available.
• qeth: Improve no_checksumming handling for layer3.
• qeth: Handle VSwitch Port Isolation error codes.
• Implement AF_IUCV SOCK_SEQPACKET support.
This update offers AF_IUCV datagram stream-oriented sockets in addition to the existing AF_IUCV
byte stream-oriented sockets. SOCK_SEQPACKET provides a sequenced, reliable, two-way
connection-based data transmission path for datagrams of fixed maximum length; a consumer is
required to read an entire packet with each input system call.
• Kernel parameters vmhalt, vmpanic, vmpoff and vmreboot are ignored.
A problem was found where an obsolete function (__setup()) was being called twice. This update
removes those function calls, and the affected kernel parameters now behave as expected.
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