[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [RFC PATCH 2/7] x86/boot: Remove gratuitous call back into low-memory code

On Thu, 2019-05-02 at 10:23 +0100, Andrew Cooper wrote:
> ...this reasoning is bogus.  We're either accessing the data itself, or
> the memcpy function, but there is no possible way to programatically
> avoid "wrong" access into the trampoline, because we're still accessing it.

Just to be clear, now I'm back at a real computer: yes there is a way
to avoid "wrong" access into the trampoline from the 64-bit C code.
It's the 6th patch in my series, for which this one is a necessary
preliminary cleanup.


It rips out all those horrid bootsym() pointer gymnastics in the 64-bit 
code, except for the limited cases where we really do need to put
things in place for the permanently AP/wakeup trampolines.

It puts all these boot-discovered variables into their own section,
then copies them back into the Xen image when the 16-bit boot code has
finished running, to be accessed from there ever after.

Which also paves the way for the no-real-mode boot not actually putting
*anything* into low memory during boot at all.

This allows us to clean up the EFI code to stop having to do that, too.

Attachment: smime.p7s
Description: S/MIME cryptographic signature

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.