Re: [PATCH v2 3/6] kexec_file: Allow skipping checksum calculation for some segments.

From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: Dave Young <dyoung@redhat.com>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Baoquan He <bhe@redhat.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Balbir Singh <bsingharora@gmail.com>,
	x86@kernel.org, kexec@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-ima-devel@lists.sourceforge.net,
	Thomas Gleixner <tglx@linutronix.de>,
	Samuel Mendoza-Jonas <sam@mendozajonas.com>,
	linuxppc-dev@lists.ozlabs.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Eric Richter <erichte@linux.vnet.ibm.com>,
	Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH v2 3/6] kexec_file: Allow skipping checksum calculation for some segments.
Date: Mon, 22 Aug 2016 00:45:31 -0300	[thread overview]
Message-ID: <2442665.06xGC9PLW9@hactar> (raw)
In-Reply-To: <20160822033643.GA30937@dhcp-128-65.nay.redhat.com>

Am Montag, 22 August 2016, 11:36:43 schrieb Dave Young:
> On 08/22/16 at 12:25am, Thiago Jung Bauermann wrote:
> > Am Montag, 22 August 2016, 11:17:45 schrieb Dave Young:
> > > On 08/18/16 at 06:09pm, Thiago Jung Bauermann wrote:
> > > > Hello Dave,
> > > > 
> > > > Thanks for your review!
> > > > 
> > > > [ Trimming down Cc: list a little to try to clear the "too many
> > > > recipients">
> > > > 
> > > >   mailing list restriction. ]
> > > 
> > > I also got "too many recipients".. Thanks for the trimming.
> > 
> > Didn't work though. What is the maximum number of recipients?
> 
> I have no idea as well..
> 
> > > > Am Donnerstag, 18 August 2016, 17:03:30 schrieb Dave Young:
> > > > > On 08/13/16 at 12:18am, Thiago Jung Bauermann wrote:
> > > > > > Adds checksum argument to kexec_add_buffer specifying whether
> > > > > > the
> > > > > > given
> > > > > > segment should be part of the checksum calculation.
> > > > > 
> > > > > Since it is used with add buffer, could it be added to kbuf as a
> > > > > new
> > > > > field?
> > > > 
> > > > I was on the fence about adding it as a new argument to
> > > > kexec_add_buffer
> > > > or as a new field to struct kexec_buf. Both alternatives make sense
> > > > to
> > > > me. I implemented your suggestion in the patch below, what do you
> > > > think?>
> > > > 
> > > > > Like kbuf.no_checksum, default value is 0 that means checksum is
> > > > > needed
> > > > > if it is 1 then no need a checksum.
> > > > 
> > > > It's an interesting idea and I implemented it that way, though in
> > > > practice all current users of struct kexec_buf put it on the stack
> > > > so
> > > > the field needs to be initialized explicitly.
> > > 
> > > No need to set it as false because it will be initialized to 0 by
> > > default?
> > 
> > As far as I know, variables on the stack are not initialized. Only
> > global
> > and static variables are.
> 
> But designated initializers will do it.

Ah, you are right! I'll provide an updated patch then. Thanks for your 
suggestion.

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

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