Re: kern/161721: [boot] compiling kernel with KVA_PAGES=512 does

On 10/19/2011 15:58, Remko Lodder wrote:
> Hello Kes,
>
> Thank you for responding to my closure. Sadly the PR list should 
> contain only
> Problem REcords (PR's) so personally I do not think a wish list item 
> should be
> kept open.
>
> Though, we might want to ask Alan whether this is something we can and 
> will work
> at or not. If the latter, well it's a pity but then we won't work on it.
>

Kes,

Your problem report doesn't include any details on the panic that 
occurs.  Could you please provide this?

Is this problem occurring with or without the use of PAE?  If I presume 
that you are not using PAE, then setting KVA_PAGES to 512 makes the 
kernel address space 2 GB in size.

Have you ever tried a slightly smaller setting for KVA_PAGES, for 
example, 508?

Remko,

I suspect this a bug, specifically, arithmetic overflow is occurring 
somewhere because 32-bit arithmetic is being used and the kernel address 
space is 2^31 bytes in size.

I would recommend that you reopen this PR, and assign it to me.  While 
you can certainly shoot yourself in the foot by messing with low-level 
configuration, like KVA_PAGES, in this case, I think we may have a bug.

Alan

>
> On Oct 19, 2011, at 8:55 PM, 扻薤膰靨蜲膻wrote:
>
>>
>> rFo> Synopsis: [boot] compiling kernel with KVA_PAGES=512 does not 
>> allow system to boot
>>
>> rFo> State-Changed-From-To: open->closed
>> rFo> State-Changed-By: remko
>> rFo> State-Changed-When: Tue Oct 18 18:27:15 UTC 2011
>> rFo> State-Changed-Why:
>> rFo> If you fiddle with kernel settings you should be aware of what 
>> you are
>> rFo> doing. The KVA pages is a problem that popped up before and is 
>> mentioned
>> rFo> enough. I do not think this is a PR worth, apologies if this offends
>> rFo> you.
>>
>> rFo> http://www.freebsd.org/cgi/query-pr.cgi?pr=161721
>>
>>
>> This is option to make FreeBSD better, so may be some developer in
>> future see this weakness and implements that.
>> If it will be closes it will be fogotten
>> So may be reopen it with very low priority as wish list, not PR
>>
>> Thank you
>>
>> -- 
>> 턠鶌馰樇鳺
>> 扻薤膰mailto:kes-kes@yandex.ru
>>
>
> -- 
> /"\   With kind regards,| remko@elvandar.org <mailto:remko@elvandar.org>
> \ /   Remko Lodder| remko@FreeBSD.org <mailto:remko@FreeBSD.org>
> X    FreeBSD| http://www.evilcoder.org
> / \   The Power to Serve| Quis custodiet ipsos custodes
>

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