Re: [PATCH 3/3] x86, crash: Allocate enough low-mem when crashkernel=high

From: Borislav Petkov <bp@alien8.de>
To: Joerg Roedel <joro@8bytes.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Joerg Roedel <jroedel@suse.de>
Subject: Re: [PATCH 3/3] x86, crash: Allocate enough low-mem when crashkernel=high
Date: Fri, 23 Jan 2015 18:02:43 +0100	[thread overview]
Message-ID: <20150123170243.GG22635@pd.tnic> (raw)
In-Reply-To: <1420555874-11506-4-git-send-email-joro@8bytes.org>

On Tue, Jan 06, 2015 at 03:51:14PM +0100, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> When the crashkernel is loaded above 4GiB in memory the
> first kernel only allocates 72MiB of low-memory for the DMA
> requirements of the second kernel. On systems with many
> devices this is not enough and causes device driver
> initialization errors and failed crash dumps. Set this
> default value to 256MiB to make sure there is enough memory

This upper limit of 256 looks arbitrary. Are we going to raise it a
couple of years from now if it becomes insufficient then?

It probably won't be easy but is there some more reliable way to
allocate enough memory for DMA on a say per-system basis or whatever...?
Probably not but let me ask it anyway.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--