public inbox for devel@edk2.groups.io
 help / color / mirror / Atom feed
From: "Gerd Hoffmann" <kraxel@redhat.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Michael Brown <mcb30@ipxe.org>,
	devel@edk2.groups.io,  Jiewen Yao <jiewen.yao@intel.com>,
	Jordan Justen <jordan.l.justen@intel.com>
Subject: Re: [edk2-devel] [PATCH 1/1] OvmfPkg/IoMmuDxe: add locking to IoMmuAllocateBounceBuffer
Date: Thu, 20 Jul 2023 10:28:13 +0200	[thread overview]
Message-ID: <57y2vtkzqkqjfoft2vn7gem527frwh3i4ymk7piaztyxlfz4fz@eqeuogfkl5vf> (raw)
In-Reply-To: <CAMj1kXGbB6te5cZjnG0pZ7B3hfgA-VBVs2P1QbOwGFBP32U4Ug@mail.gmail.com>

> > >   mReservedMemBitmap &= (UINT32)(~MapInfo->ReservedMemBitmap);
> >
> > I'd expect modern compilers optimize that to a single instruction,
> 
> You mean something along the lines of
> 
>   andl %reg, mReservedMemBitmap(%rip)
> 
> right?

Yes.

> > but
> > yes, it's not guaranteed to happen, the compiler can choose to generate
> > a series of load + and + store instructions instead.
> 
> That is sadly all we have on ARM, unless you use LSE atomics, which
> are optional in the architecture so we never use those in EDK2.

ARM means v7 only or both v7+v8?

take care,
  Gerd



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#107089): https://edk2.groups.io/g/devel/message/107089
Mute This Topic: https://groups.io/mt/100233359/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-



  parent reply	other threads:[~2023-07-20  8:28 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-19 11:33 [edk2-devel] [PATCH 1/1] OvmfPkg/IoMmuDxe: add locking to IoMmuAllocateBounceBuffer Gerd Hoffmann
2023-07-19 16:04 ` Michael Brown
2023-07-19 16:31   ` Gerd Hoffmann
2023-07-19 16:52     ` Ard Biesheuvel
2023-07-19 17:40       ` Michael Brown
2023-07-19 22:06         ` Ard Biesheuvel
2023-07-20  8:30           ` Gerd Hoffmann
2023-07-20  8:28       ` Gerd Hoffmann [this message]
2023-07-20 12:45         ` Ard Biesheuvel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-list from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=57y2vtkzqkqjfoft2vn7gem527frwh3i4ymk7piaztyxlfz4fz@eqeuogfkl5vf \
    --to=devel@edk2.groups.io \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox