From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <1da684cfe23ffc1ad92ffebc6837646b@9netics.com>
To: 9fans@9fans.net
Date: Sun, 21 Jun 2015 15:02:15 -0700
From: Skip Tavakkolian <9nut@9netics.com>
In-Reply-To: <20150621233253.1d74c860@zinc.9fans.fr>
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Subject: Re: [9fans] compiling xen3 with more recent pc kernel
Topicbox-Message-UUID: 5a197b70-ead9-11e9-9d60-3106f5b1d025

thanks.

i saw the note and was wondering if for xen3 it could be
stubbed out.

>> i had to make the following changes to the kernel for xen3 to match up
>> to recent labs pc kernel and to compile successfully.  can anyone
>> verify the changes are correct?  (i could to a smoke test on EC2, but
>> don't feel adventurous at the moment)
>
> The evenaddr function in trap.c should be replaced by validalign:
>
> void
> validalign(uintptr addr, unsigned align)
> {
> 	/*
> 	 * Plan 9 is a 32-bit O/S, and the hardware it runs on
> 	 * does not usually have instructions which move 64-bit
> 	 * quantities directly, synthesizing the operations
> 	 * with 32-bit move instructions. Therefore, the compiler
> 	 * (and hardware) usually only enforce 32-bit alignment,
> 	 * if at all.
> 	 *
> 	 * Take this out if the architecture warrants it.
> 	 */
> 	if(align == sizeof(vlong))
> 		align = sizeof(long);
>
> 	/*
> 	 * Check align is a power of 2, then addr alignment.
> 	 */
> 	if((align != 0 && !(align & (align-1))) && !(addr & (align-1)))
> 		return;
> 	postnote(up, 1, "sys: odd address", NDebug);
> 	error(Ebadarg);
> 	/*NOTREACHED*/
> }
>
> This is a change done by Jim McKie on 2014-05-15.
>
> --
> David du Colombier