linux-kernel - Re: Edited kexec_load(2) [kexec_file

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Message-ID: <20150128144803.GC15342@redhat.com>
Date:	Wed, 28 Jan 2015 09:48:03 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	"linux-man@...r.kernel.org" <linux-man@...r.kernel.org>,
	kexec@...ts.infradead.org, Andy Lutomirski <luto@...capital.net>,
	Dave Young <dyoung@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: Edited kexec_load(2) [kexec_file_load()] man page for review

On Wed, Jan 28, 2015 at 09:04:38AM +0100, Michael Kerrisk (man-pages) wrote:

Hi Michael,

[..]
> >> * the number of bytes copied from userspace is min(bufsz, memsz)
> > 
> > Yes. bufsz can not be more than memsz. There is a check to validate
> > this in kernel.
> > 
> > 	result = -EINVAL;
> > 	for (i = 0; i < nr_segments; i++) {
> > 		if (image->segment[i].bufsz > image->segment[i].memsz)
> > 			return result;
> > 	}
> 
> Okay. So it's more precise to leave discussion of min(bufz, memsz) 
> out of the man page just to say: bufsz bytes are transferred; 
> if bufsz < memsz, then the excess bytes in the target region are 
> filled with zeros. Right?

Sounds good.

[..]
> > Both mem and memsz need to be page aligned.
> 
> And the error if not is EADDRNOTAVAIL, right?

Yes.

> 
> >> And one further question. Other than the fact that they are used with 
> >> different system calls, what is the difference between KEXEC_ON_CRASH 
> >> and KEXEC_FILE_ON_CRASH?
> > 
> > Right now I can't think of any other difference. They both tell respective
> > system call that this kernel needs to be loaded in reserved memory region
> > for crash kernel.
> 
> Okay.
> 
> I've made various adjustments to the page in the light of your comments 
> above. Thanks!

Thank you for following it up and improving kexec man page.

Thanks
Vivek
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