Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is notenough ram for it

From: H. Peter Anvin
Date: Thu Jan 31 2013 - 14:37:49 EST


On 01/31/2013 11:28 AM, Shuah Khan wrote:
> On Mon, Jan 28, 2013 at 8:44 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>> On Mon, Jan 28, 2013 at 6:27 PM, Shuah Khan <shuahkhan@xxxxxxxxx> wrote:
>>> On Thu, Jan 24, 2013 at 2:50 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>>>
>>> Your for-x86-boot git boots on AMD system I have. However, with
>>> memmap=4095$1M option, it panics very early in boot. I don't have
>>> physical access to the console and I will try to get you the panic
>>> information tomorrow.
>>
>> panic is good, but it is supposed some kind of late..
>>
>
> It is a very early panic, however it is not specific to your git. It
> happens on 3.4, 3.8-rc4. You can disregard the early panic for your
> git.
>

Knocking out 4095 bytes is kind of an unusual action, however, assuming
the kernel is running at 16 MiB as normal then it should just work...

memmap=4095M$1M as was shown later is another matter... there the kernel
will be living inside the reserved region, and yes, at that point it is
panic time since there is nothing the kernel can do about it.

-hpa


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