linux-kernel - Re: [PATCH] x86, efi: print debug values in Kib not MB

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Message-ID: <20140729222932.GA17481@pd.tnic>
Date:	Wed, 30 Jul 2014 00:29:32 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Prarit Bhargava <prarit@...hat.com>
Cc:	linux-kernel@...r.kernel.org, lszubowi@...hat.com,
	Matt Fleming <matt.fleming@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-efi@...r.kernel.org
Subject: Re: [PATCH] x86, efi: print debug values in Kib not MB

On Tue, Jul 29, 2014 at 01:09:21PM -0400, Prarit Bhargava wrote:
> The current debug print in EFI does
> 
> [    0.000000] efi: mem84: type=3, attr=0xf, range=[0x00000000645b5000-0x00000000645fb000) (0MB)
> 
> and rounds off the size to 0MB and isn't very useful.  We should print this in
> Kib.  After applying this patch we get better info with
> 
> [    0.000000] efi: mem84: type=3, attr=0xf, range=[0x00000000645b5000-0x00000000645fb000) (280kiB)

Turning this into kiB unconditionally won't always work ok:

First of all, there might be something which parses that output so I'd
make sure I'm not breaking that. Maybe fwts... Matt will know.

Then, I have an UEFI region which is > 13G:

[    0.000000] efi: mem42: type=7, attr=0xf, range=[0x0000000100000000-0x0000000450000000) (13568MB)


With your patch it is even worse:

[    0.000000] efi: mem42: type=7, attr=0xf, range=[0x0000000100000000-0x0000000450000000) (13893632kiB)


I'd guess you'll have to go all out and do this properly. :-)

Something like showing the highest unit which is still > 1. In the above
case, this should be (13GB) or maybe even introduce fractions.

Depends on how involved this output should be.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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