On 11/20/23 05:59, Dhaval Sharma wrote:
> Did you mean to add it as a memory type by itself like
> EFI_MEMORY_TYPE_INFORMATION?
Yes, a new enum constant for EFI_MEMORY_TYPE.
(It wasn't a "loaded question", just wanted to understand the reasoning.)
> My interpretation of Memory Type is that it is more of SW usability
> construct while Memory Attr is more of HW behavioural construct.
> Together they define how a memory region can be used.
I guess it's hard to tell apart. The SPM definition (visible in the
context below, from your earlier email) does seem like a software
usability construct ("avoid allocating for ...").
But, I truly don't know. I guess I was only trying to gauge if I could
be a useful reviewer for this series; probably not.
Thanks!
Laszlo
>
> On Fri, Nov 17, 2023 at 1:55 PM Laszlo Ersek <[email protected]
> <mailto:[email protected]>> wrote:
>
> On 11/17/23 09:07, Dhaval Sharma wrote:
> > Hi,
> > I wanted to revisit this thread and I am maintaining the context as
> > there are a lot of details already mentioned here
> regarding EFI_MEMORY_SP.
> > Other than what has been addressed here, we also would like to have an
> > option in edk2 to *avoid* using this type of memory for its own
> > purposes. This seems like one of the motivations for original request
> > and is being honored by OS today but not edk2 as it does not have any
> > specific implementation today which takes this attribute into
> consideration.
> > I would like to add PCD based implementation which informs edk2 NOT to
> > use this memory for its own purposes and leave it alone (as still
> > available memory to OS).
> >
> > Specific-purpose memory (SPM). The memory is earmarked for
> > specific purposes such as for specific device drivers or applications.
> > The SPM attribute serves as a hint to the OS to avoid allocating this
> > memory for core OS data or code that can not be relocated.
> > Prolonged use of this memory for purposes other than the intended
> > purpose may result in suboptimal platform performance.
> >
> > Some more context:
> > https://lwn.net/Articles/784971/ <https://lwn.net/Articles/784971/>
>
> Why was EFI_MEMORY_SP introduced as a memory attribute, rather than its
> own memory type?
>
> Laszlo
>
>
>
> --
> Thanks!
> =D
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