Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
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- Subject: Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- From: Yinghai Lu <yinghai@xxxxxxxxxx>
- Date: Fri, 16 Mar 2012 12:01:40 -0700
- Cc: "H. Peter Anvin" <hpa@xxxxxxxxxx>, mingo@xxxxxxxxxx, mjg@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, keithp@xxxxxxxxxx, rui.zhang@xxxxxxxxx, huang.ying.caritas@xxxxxxxxx, stable@xxxxxxxxxxxxxxx, tglx@xxxxxxxxxxxxx, linux-tip-commits@xxxxxxxxxxxxxxx
- In-reply-to: <1331923006.4041.30.camel@mfleming-mobl1.ger.corp.intel.com>
On Fri, Mar 16, 2012 at 11:36 AM, Matt Fleming <matt.fleming@xxxxxxxxx> wrote:
> On Thu, 2012-03-15 at 10:54 -0700, Yinghai Lu wrote:
>> > if (end <= max_low_pfn << PAGE_SHIFT)
>> > max_low_pfn_mapped = last_pfn_mapped;
>>
>> why max_low_pfn is used here?
>
> The idea is that we only want to update max_low_pfn_mapped when we've
> mapped a region at or below max_low_pfn. This maintains compatibility
> with behaviour prior to this patch.
>
>> > The max_low_pfn checks are only for CONFIG_X86_32 so that the behaviour
>> > is the same as before this patch, i.e. we don't try to map above
>> > max_low_pfn.
>>
>> ok, to simplify the code, in setup.c you could move
>> #ifdef CONFIG_X86_64
>> if (max_pfn > max_low_pfn) {
>> /* can we preseve max_low_pfn ?*/
>> max_low_pfn = max_pfn;
>> }
>> #endif
>>
>> before calling new init_memory_mapping()...
>>
>> so you could remove the #idef. in init_memory_mapping.
>
> Hmm.. if we do this then max_low_pfn_mapped will be set to max_pfn on
> CONFIG_X86_64 by the time we've finished looping in
> init_memory_mapping(). This is not how things work currently. Will that
> cause a problem?
oh, before this patch could be applied, you need to make sure all
max_low_pfn_mapped reference
is removed.
current assumption is under max_low_pfn_mapped all mem is mapped.
now with this patch, that assumption is not right anymore.
Yinghai
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- References:
- [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- From: tip-bot for Matt Fleming
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
- Re: [tip:x86/urgent] x86, efi: Delete efi_ioremap() and fix CONFIG_X86_32 oops
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