Is the 16bit code segment descriptor needed in early DXE before CpuDxe (DXE MP)?
> -----Original Message----- > From: Tom Lendacky <thomas.lenda...@amd.com> > Sent: Thursday, November 21, 2019 4:07 AM > To: devel@edk2.groups.io > Cc: Justen, Jordan L <jordan.l.jus...@intel.com>; Laszlo Ersek > <ler...@redhat.com>; Ard Biesheuvel > <ard.biesheu...@linaro.org>; Kinney, Michael D <michael.d.kin...@intel.com>; > Gao, Liming <liming....@intel.com>; Dong, > Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Brijesh Singh > <brijesh.si...@amd.com>; Wang, Jian J > <jian.j.w...@intel.com>; Wu, Hao A <hao.a...@intel.com>; Bi, Dandan > <dandan...@intel.com> > Subject: [RFC PATCH v3 33/43] MdeModulePkg: Reserve a 16-bit protected mode > code segment descriptor > > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 > > SEV-ES guest AP boot support needs to transition from 64-bit long mode > into 16-bit real mode. This will require a 16-bit code segment descriptor. > Reserve one of the spare segment descriptors (0x28) for this purpose. > > Cc: Jian J Wang <jian.j.w...@intel.com> > Cc: Hao A Wu <hao.a...@intel.com> > Cc: Dandan Bi <dandan...@intel.com> > Cc: Liming Gao <liming....@intel.com> > Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> > --- > MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c > b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c > index 284b34818ca7..c9cf2e36214f 100644 > --- a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c > +++ b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c > @@ -33,7 +33,7 @@ GLOBAL_REMOVE_IF_UNREFERENCED IA32_GDT gGdtEntries[] = { > /* 0x10 */ {{0xffff, 0, 0, 0xf, 1, 0, 1, 0xf, 0, 0, 1, 1, 0}}, > //linear code segment descriptor > /* 0x18 */ {{0xffff, 0, 0, 0x3, 1, 0, 1, 0xf, 0, 0, 1, 1, 0}}, > //system data segment descriptor > /* 0x20 */ {{0xffff, 0, 0, 0xa, 1, 0, 1, 0xf, 0, 0, 1, 1, 0}}, > //system code segment descriptor > -/* 0x28 */ {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, > //spare segment descriptor > +/* 0x28 */ {{0xffff, 0, 0, 0xa, 1, 0, 1, 0xf, 0, 0, 0, 1, 0}}, > //system code16 segment descriptor > /* 0x30 */ {{0xffff, 0, 0, 0x2, 1, 0, 1, 0xf, 0, 0, 1, 1, 0}}, > //system data segment descriptor > /* 0x38 */ {{0xffff, 0, 0, 0xa, 1, 0, 1, 0xf, 0, 1, 0, 1, 0}}, > //system code segment descriptor > /* 0x40 */ {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, > //spare segment descriptor > -- > 2.17.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#52151): https://edk2.groups.io/g/devel/message/52151 Mute This Topic: https://groups.io/mt/60973140/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
