From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([66.187.233.31]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1JEpms-0006PH-Oq for kexec@lists.infradead.org; Tue, 15 Jan 2008 17:41:22 +0000 Date: Tue, 15 Jan 2008 12:37:53 -0500 From: Vivek Goyal Subject: Re: Kexec command line length Message-ID: <20080115173753.GB24435@redhat.com> References: <20080114134303.GA947@hmsreliant.think-freely.org> <20080115152710.GA24435@redhat.com> <20080115170950.GA24359@hmsendeavour.rdu.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20080115170950.GA24359@hmsendeavour.rdu.redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org+dwmw2=infradead.org@lists.infradead.org To: Neil Horman Cc: kexec@lists.infradead.org, Neil Horman On Tue, Jan 15, 2008 at 12:09:50PM -0500, Neil Horman wrote: > On Tue, Jan 15, 2008 at 10:27:10AM -0500, Vivek Goyal wrote: > > On Mon, Jan 14, 2008 at 08:43:03AM -0500, Neil Horman wrote: > > > Hey all- > > > Regarding this bug: > > > http://bugzilla.kernel.org/show_bug.cgi?id=9641 > > > I'd like to look into putting together a patch for it, and wanted to > > > solicit comments for the best way to go about doing it. Currently I've got it > > > fixed up in the Red Hat tree by bumping COMMAND_LINE_SIZE to 2048 and > > > eliminating the reserved buffer of the x86_linux_faked_param_header, which works > > > well, but isn't backwards compatible as Bernhard pointed out. Given that extra > > > constraint, I thought it woudl e best to unify the command line and reserved > > > buffers in x86_linux_faked_param_header to one contiguour 2048 byte block and > > > maintain a separate variable that defines the command line length based on a > > > parsing of the UTS_VERSION. Does that sound reasonable to everyone, or is there > > > a better way that someone has in mind? > > > > > > > Hi Neil, > > > > Looking at UTS_VERSION and then deciding the command line length seems > > ok. > > > > When I look at inclue/asm-x86/bootparam.h in kernel, area starting from > > 0x2d0 to all the way up to 4K has been reserved for e820 maps and EDD buf. > > > > Does that mean newer boot loaders are putting command line outside of > > 4K page and only putting the pointer to cmdline in 4K page. If that's the > > case then we might have to do the same for kexec. > > > > That would seem to be the case yes, although it appears the kernel still > supports the old boot protocol if you want to restrict the command line length > to the old 256 chars (see copy_boot_data) > If that's the case then we probably should not be merging command_line and reserved area. Instead we might have to put command line somewhere else and pass the pointer to it in param page. If command line is with-in 256, then we can continue to pass it in param page. Thanks Vivek _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec