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parisc: Document rules regarding checksum of HPMC handler 

Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2018-04-18 15:46:41 +02:00
parent 89e050c87d
commit 41dbee81c8
1 changed files with 11 additions and 0 deletions
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11
arch/parisc/kernel/traps.c
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@ -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;