volatile means do not optimize into a register. The compiler must perform the actual memory access every time.
Mike > -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Ni, Ray > Sent: Sunday, February 18, 2024 7:06 PM > To: Zhou, Jianfeng <jianfeng.z...@intel.com>; devel@edk2.groups.io > Cc: Laszlo Ersek <ler...@redhat.com>; Kumar, Rahul R > <rahul.r.ku...@intel.com>; Gerd Hoffmann <kra...@redhat.com> > Subject: Re: [edk2-devel] [PATCH] UefiCpuPkg: code refine > > > > - PleB->Uint64 = LocalPleB.Uint64; > > > > + *(volatile UINT64 *)&(PleB->Uint64) = LocalPleB.Uint64; > > Jianfeng, > If "volatile" is to tell compiler to generate single "mov" instruction > for > the assignment. > > I am curious how it works in 32bit env where the general purpose > registers are > 32bit width? > > Thanks, > Ray > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115582): https://edk2.groups.io/g/devel/message/115582 Mute This Topic: https://groups.io/mt/104256295/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
