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Commit 41dbee81 authored by Helge Deller's avatar Helge Deller
Browse files

parisc: Document rules regarding checksum of HPMC handler 



Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 89e050c8

arch/parisc/kernel/traps.c

+11 −0
Original line number Diff line number Diff line
@@ -837,6 +837,17 @@ void __init initialize_ivt(const void *iva) 
	if (pdc_instr(&instr) == PDC_OK)

		ivap[0] = instr;



	/*

	 * Rules for the checksum of the HPMC handler:

	 * 1. The IVA does not point to PDC/PDH space (ie: the OS has installed

	 *    its own IVA).

	 * 2. The word at IVA + 32 is nonzero.

	 * 3. If Length (IVA + 60) is not zero, then Length (IVA + 60) and

	 *    Address (IVA + 56) are word-aligned.

	 * 4. The checksum of the 8 words starting at IVA + 32 plus the sum of

	 *    the Length/4 words starting at Address is zero.

	 */



	/* Compute Checksum for HPMC handler */

	length = os_hpmc_size;

	ivap[7] = length;