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    SubjectRe: [RFC PATCH v4 26/28] x86: Allow kexec to be used with SME
    Add kexec list..

    On 03/01/17 at 05:25pm, Dave Young wrote:
    > Hi Tom,
    >
    > On 02/17/17 at 10:43am, Tom Lendacky wrote:
    > > On 2/17/2017 9:57 AM, Konrad Rzeszutek Wilk wrote:
    > > > On Thu, Feb 16, 2017 at 09:47:55AM -0600, Tom Lendacky wrote:
    > > > > Provide support so that kexec can be used to boot a kernel when SME is
    > > > > enabled.
    > > >
    > > > Is the point of kexec and kdump to ehh, dump memory ? But if the
    > > > rest of the memory is encrypted you won't get much, will you?
    > >
    > > Kexec can be used to reboot a system without going back through BIOS.
    > > So you can use kexec without using kdump.
    > >
    > > For kdump, just taking a quick look, the option to enable memory
    > > encryption can be provided on the crash kernel command line and then
    >
    > Is there a simple way to get the SME status? Probably add some sysfs
    > file for this purpose.
    >
    > > crash kernel can would be able to copy the memory decrypted if the
    > > pagetable is set up properly. It looks like currently ioremap_cache()
    > > is used to map the old memory page. That might be able to be changed
    > > to a memremap() so that the encryption bit is set in the mapping. That
    > > will mean that memory that is not marked encrypted (EFI tables, swiotlb
    > > memory, etc) would not be read correctly.
    >
    > Manage to store info about those ranges which are not encrypted so that
    > memremap can handle them?
    >
    > >
    > > >
    > > > Would it make sense to include some printk to the user if they
    > > > are setting up kdump that they won't get anything out of it?
    > >
    > > Probably a good idea to add something like that.
    >
    > It will break kdump functionality, it should be fixed instead of
    > just adding printk to warn user..
    >
    > Thanks
    > Dave

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