linux-kernel - Re: [PATCH] x86: only load initrd above 4g on second try

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Message-ID: <53FE1A2B.80204@zytor.com>
Date:	Wed, 27 Aug 2014 10:49:31 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Matt Fleming <matt.fleming@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Mantas Mikulėnas <grawity@...il.com>,
	Anders Darander <anders@...rgestorm.se>,
	linux-efi@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: only load initrd above 4g on second try

On 08/26/2014 03:05 PM, Yinghai Lu wrote:
> 
> The firmware has bug and can use buffer above 4G to read files.
> and if the file size is 512 bytes alignment, then reading could go through.
> 

File size, or alignment?  Different things.  Again, your patch
description is not just incomplete, but seems to be actively misleading.

This does, however, suggest at least two possible solutions:

1. We can read the initramfs into a temporary buffer and memcpy() it to
the target.

2. We might be able to align the initramfs buffer to a 512-byte section
and then round up the size.

The 512 bytes here is probably a hardware sector, I'm not sure how this
will play on 4K-hard-sectored media, although those are few and far between.

	-hpa

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