linux-kernel - Re: [RFC] ELF Relocatable x86 and x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 04 Aug 2006 16:47:10 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Dave Jones <davej@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>, vgoyal@...ibm.com,
	fastboot@...l.org, linux-kernel@...r.kernel.org,
	Horms <horms@...ge.net.au>,
	Jan Kratochvil <lace@...kratochvil.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Magnus Damm <magnus.damm@...il.com>,
	Linda Wang <lwang@...hat.com>
Subject: Re: [RFC] ELF Relocatable x86 and x86_64 bzImages

Dave Jones wrote:
> On Fri, Aug 04, 2006 at 05:14:37PM -0600, Eric W. Biederman wrote:
> 
>  > I guess the practical question is do people see a real performance benefit
>  > when loading the kernel at 4MB?
> 
> Linus claimed lmbench saw some huge wins. Others showed that for eg,
> a kernel compile took the same amount of time, so take from that what you will..
> 
>  > Possibly the right solution is to do like I did on x86_64 and simply remove
>  > CONFIG_PHYSICAL_START, and always place the kernel at 4MB, or something like
>  > that.
>  > 
>  > The practical question is what to do to keep the complexity from spinning
>  > out of control.  Removing CONFIG_PHYSICAL_START would seriously help with
>  > that.
> 
> Given the two primary uses of that option right now are a) the aforementioned
> perf win and b) building kexec kernels, I doubt anyone would miss it once
> we go relocatable ;-)
> 

We DO want the performance gain with a conventional bootloader.  The 
perf win is about the location of the uncompressed kernel, not the 
compressed kernel.

	-hpa

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/