linux-kernel - Re: [PATCH v2] x86, boot: add hex output for debugging

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Date:	Fri, 31 Oct 2014 16:45:31 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Kees Cook <keescook@...omium.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Vivek Goyal <vgoyal@...hat.com>,
	Junjie Mao <eternal.n08@...il.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v2] x86, boot: add hex output for debugging

On Fri, Oct 31, 2014 at 04:31:32PM -0700, Yinghai Lu wrote:
> On Fri, Oct 31, 2014 at 1:58 PM, Kees Cook <keescook@...omium.org> wrote:
> > This is useful for reporting various addresses or other values while
> > debugging early boot. For example, when CONFIG_X86_VERBOSE_BOOTUP is set,
> > this is now visible at boot time:
> >
> >         early console in setup code
> >         early console in decompress_kernel
> >         input_data: 0x0000000001e1526e
> >         input_len: 0x0000000000732236
> >         output: 0x0000000001000000
> >         output_len: 0x0000000001535640
> >         run_size: 0x00000000021fb000
> >         KASLR using RDTSC...
> >
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> > Since this displays run_size, this patch depends on Junjie Mao's patch
> > "x86, kaslr: Prevent .bss from overlaping initrd"
> >
> > ---
> >  arch/x86/boot/compressed/misc.c | 24 ++++++++++++++++++++++++
> >  arch/x86/boot/compressed/misc.h | 11 +++++++++++
> >  2 files changed, 35 insertions(+)
> ...
> 
> We can reuse printf.c in arch/x86/boot.
> 
> I had attached one in local tree for a while. or even sent it before
> several years ago.

I don't think we need the full generality of printf in the decompression
stub.  I prefer Kees' patch, though I'd still like to see __puthex made
conditional.

- Josh Triplett
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