Linux Driver for APIC Authors: Berkley Shands, John DeHart, - - PDF document

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Linux Driver for APIC

• Authors: Berkley Shands, John DeHart,

Rezwani Kabir

• Linux Kernel versions 2.2.X (user mode
• nly)
• 2.3.99-pre6 (stable)
• 2.4.0-test1 (intel/alpha with patches)
• 2.4.0-test2 (intel only)

Linux Driver Features

• Supports multiple apics in one box
• Supports 32 or 64 bit machines (intel

X86 and Alpha (XP1000))

• AAL5 frames up to 65K long
• AAL0 single cell (not tested)
• Linux ATM 0.77 compatible
• 4Kb input buffers

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Linux Driver

• 1MB pool for Descriptors
• 1MB pool for shadow set
• 1MB pool for input frames (permanently

allocated)

Known Bugs

• High input cell rates (blasting) hang up

the interrupt driver (fix available)

• Alpha PCI bus and Bridges –

APIC_STUCK_BIT

• Not module loadable (I have not tried ☺)
• Syscall(APIC, RESET) hangs IP driver.

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Remaining Work

• Remove debug statements
• Tune for smaller vs larger machines
• Test AAL0 interface
• Package for Distribution

Driver Details

• Ap_vcc + atm_vcc + ap_dev
• Pool buffers AAL5 fixed size, never

reclaimed (reused only out of shadow set)

• Larger MTU in ifconfig (up to 65K)

Performance!

• Slab.c updated for big entries

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