linux-kernel - Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is not enough ram for it

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Date:	Mon, 7 Jan 2013 13:30:22 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Shuah Khan <shuahkhan@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>, Jan Kiszka <jan.kiszka@....de>,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org, Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is not
 enough ram for it

On Mon, Jan 7, 2013 at 12:32 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>>  2). The check for 1MB is suspect. Why only 1MB? You mentioned it is
>>      b/c of crashkernel_low=72M (which I am not seeing in v3.8 kernel-parameters.txt?
>>      Is that part of your mega-patchset?). Anyhow, there seems to be a disconnect -
>>      what if the user supplied crashkernel_low=27M? Perhaps the 'is_enough'
>>      should also parse the bootparams to double-check that there is enough
>>      low-mem space? But then if the kernel grows then 72M might not be enough -
>>      you might need 82M with 3.9.
>
> again, could with memmap= include or exclude case, so parse boot command line
> is not going to handle all the case.

replace the hardcoded 1M checking, please check attached -v3.

Thanks

Yinghai

Download attachment "auto_switch_off_swiotlb_v3.patch" of type "application/octet-stream" (5014 bytes)