linux-kernel - Re: [RFC v2 0/2] Early use of boot service memory

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Message-ID: <528E94D1.2050809@zytor.com>
Date:	Thu, 21 Nov 2013 15:18:41 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>,
	Jerry Hoemann <jerry.hoemann@...com>
CC:	rob@...dley.net, tglx@...utronix.de, mingo@...hat.com,
	x86@...nel.org, matt.fleming@...el.com, yinghai@...nel.org,
	akpm@...ux-foundation.org, bp@...e.de, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	penberg@...nel.org, mingo.kernel.org@...il.com, vgoyal@...hat.com
Subject: Re: [RFC v2 0/2] Early use of boot service memory

On 11/21/2013 03:07 PM, Matthew Garrett wrote:
> On Thu, Nov 21, 2013 at 02:01:24PM -0700, Jerry Hoemann wrote:
>>
>> Some platform have firmware that violates the UEFI spec and access boot
>> service code or data segments after the system has called ExitBootServices().
>> The call to efi_reserve_boot_services in setup_arch is a workaround to
>> avoid using boot service memory until after the kernel has done
>> SetVirtualAddressMap.  However, this reservation fragments memory
>> which can cause large allocations early in boot (e.g. crash kernel)
>> to fail.
> 
> This is a problem we have to solve, but I don't think this is the right 
> way to solve it. Why do we not just reattempt to perform the allocation 
> immediately after we've freed the boot services regions?
> 

Wouldn't the memory map already have gotten scrambled all to hell by then?

	-hpa

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