linux-kernel - Re: [PATCH 2/5 V6] x86/ioremap: strengthen the logic in early_memremap_pgprot

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Message-ID: <a09a3a21-9156-ce96-b7ef-9f7e7cda12b3@redhat.com>
Date:   Wed, 5 Sep 2018 22:04:49 +0800
From:   lijiang <lijiang@...hat.com>
To:     Dave Young <dyoung@...hat.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
        hpa@...or.com, ebiederm@...ssion.com, joro@...tes.org,
        thomas.lendacky@....com, kexec@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, bhe@...hat.com,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: [PATCH 2/5 V6] x86/ioremap: strengthen the logic in
 early_memremap_pgprot_adjust() to adjust encryption mask

在 2018年09月05日 14:46, Dave Young 写道:
> [snip]
>>
>> As previously mentioned, there are also many differences between kexec and kdump. In general,
>> kexec needs to look at all of available physical memory, but kdump doesn't need.
>>
>> For kexec, kexec-tools will read /sys/firmware/memmap and recreate the e820 ranges for the 2nd
>> kernel. If it fails, will use /proc/iomem.
>>
>> For kdump, kexec-tools will read /proc/iomem and recreate the e820 ranges for kdump kernel.
>> BTW: we can not get the range of persistent memory from /proc/iomem. So e820 ranges don't contain
>> the persistent memory in kdump kernel, this is the real reason why i need to strengthen the logic
>> of adjusting memory encryption mask.
> 
> "persistent memory" is different, I think you meant about some reserved
> memory instead
> 
>>
>> If kexec-tools also use /sys/firmware/memmap for kdump(like kexec), kdump kernel can also work
>> without a fix, but the kexec-tools will have to be modified. Are you sure that you want me to
>> fix kexec-tools instead of kernel?
> 
> Yes, please fix kexec-tools to pass reserved ranges in e820, you will
> not need this patch then.
> 

This might be a kexec-tools bug, i have posted a patch for kexec-tools(please check kexec@...ts.infradead.org).
Thanks.

> Thanks
> Dave
>