User`s guide

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Known Issues
78 RedHawk Linux Version 5.4 Release Notes
irqbalance
The irqbalance feature is disabled on RedHawk Linux. This Red Hat feature is meant to
distribute interrupts equally across CPUs. It does not honor the IRQ affinity masks set up in
/proc/irq/irq#/smp_affinity and therefore will cause interrupts to be routed to
shielded CPUs.
This feature can be enabled/disabled at boot time with:
chkconfig irqbalance {on|off}
as well as started/stopped while the system is running with:
service irqbalance {start|stop}
Boot Problems with Monitor-embedded USB Hub and Flash Memory Reader
An iHawk system with a USB hub embedded within its attached monitor that includes a flash
memory reader will fail to boot if the flash media is not installed. Once the flash media is
installed, the system will boot.
Compatibility Issues for Ada programs
RedHawk 5.4 is based on Red Hat Enterprise Linux 5.4. Binary and source compatibility issues
exist for MAXAda programs between RHEL 3.0 and RHEL 5.4.
Please see the Compatibility section in the MAXAda for RedHawk Linux Version 3.5.1 Release
Notes, publication number 0898357-3.5.1, for details.
Inactive Virtual Terminal State After Changing Run Levels
Note that on some systems, changing from run-level 5 to run-level 3 may place the VGA
console onto an inactive virtual terminal (e.g. /dev/tty8). If this happens, switching to an active
virtual terminal will allow normal system operation to continue; press Ctrl-Alt-1 to switch to
virtual terminal 1.
Instability with NVIDIA 8174 Driver and NVS400 Graphics Card
Some stability problems have been observed when using the Model 8174 NVIDIA driver with
the NVIDIA NVS400 graphics card in Dell 6800 systems. If you experience system instability
with this configuration, you will likely need to downgrade to version 7676 of the NVIDIA
driver. Contact Concurrent technical support for additional information and assistance.
Excessive ksoftirqd Runs Affecting Determinism
In RedHawk 4.1, the IP route cache table size was changed from a fixed size of 4K entries to a
dynamic size based on the amount of available memory. With 4 GB of memory, this table is
sized at 128K entries. Every 10 minutes, a flush of that table is initiated. The approximate time
to flush 4K entries is 1.5ms every 10 minutes. If the table is sized at 128K entries, this time can
be in the area of 10ms to 15ms every 10 minutes. This can be problematic if network
determininsm is at issue, especially in a single CPU system.
If this is an issue, the IP route cache table can be set to a fixed size using the grub command
rhash_entries=n, where n is the number of table entries; e.g., rhash_entries=4096
for 4K entries.