From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH] i40e: fix shared code compile warning Date: Tue, 24 Jun 2014 12:06:07 +0200 Message-ID: <4332738.s42vW08oSG@xps13> References: <1403587377-10287-1-git-send-email-jing.d.chen@intel.com> <2859281.xMAtdAgJn8@xps13> <4341B239C0EFF9468EE453F9E9F4604D01595D45@shsmsx102.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Cc: dev-VfR2kkLFssw@public.gmane.org To: "Chen, Jing D" Return-path: In-Reply-To: <4341B239C0EFF9468EE453F9E9F4604D01595D45-E2R4CRU6q/6iAffOGbnezLfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 2014-06-24 09:47, Chen, Jing D: > From: Thomas Monjalon [mailto:thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org]=20 > > 2014-06-24 13:22, Chen Jing D: > > > +CFLAGS_i40e_lan_hmc.o +=3D -Wno-error > >=20 > > I know we shouldn't modify base drivers. But this one seems to be a= n > > important error. In such case, we already modified base driver. Rec= ently: > > http://dpdk.org/ml/archives/dev/2014-June/003498.html >=20 > I think it's different. The logic is right after adding the patch. Be= low is > my finding.=20 =20 > In this case, it met the error when compile on 32-bits OS. The messag= e is : >=20 > /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_p= md_i40e > /i40e/i40e_lan_hmc.c: In function =E2=80=98i40e_write_qword=E2=80=99:= > /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_p= md_i40 > e/i40e/i40e_lan_hmc.c:917: error: integer constant is too large for =E2= =80=98long=E2=80=99 > type > /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_p= md_i40 > e/i40e/i40e_lan_hmc.c: In function =E2=80=98i40e_read_qword=E2=80=99:= > /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_p= md_i40 > e/i40e/i40e_lan_hmc.c:1097: error: integer constant is too large for = =E2=80=98long=E2=80=99 > type=20 > I found the code that cause errors. 'mask' is 'uint64_t' type and is > assigned to value 0Xffff_ffff_ffff_ffff. Compiler assumes the constan= t is > 'int' type by default. If changed it to oxffff_ffff_ffff_ffffULL, the= > warning will be gone. =20 > =09if (ce_info->width < 64) > =09=09mask =3D ((u64)1 << ce_info->width) - 1; > =09else > =09=09mask =3D 0xFFFFFFFFFFFFFFFF; >=20 > besides that, I dis-assembler the code with the patch and get below s= egment. > It seems right.=20 =20 > if (ce_info->width < 64) > 1946: 8b 45 0c mov 0xc(%ebp),%eax > 1949: 0f b7 40 04 movzwl 0x4(%eax),%eax > 194d: 66 83 f8 3f cmp $0x3f,%ax > 1951: 77 30 ja 1983 > mask =3D ((u64)1 << ce_info->width) - 1; > 1953: 8b 45 0c mov 0xc(%ebp),%eax > 1956: 0f b7 40 04 movzwl 0x4(%eax),%eax > 195a: 0f b7 c8 movzwl %ax,%ecx > 195d: b8 01 00 00 00 mov $0x1,%eax > 1962: ba 00 00 00 00 mov $0x0,%edx > 1967: 0f a5 c2 shld %cl,%eax,%edx > 196a: d3 e0 shl %cl,%eax > 196c: f6 c1 20 test $0x20,%cl > 196f: 74 04 je 1975 > 1971: 89 c2 mov %eax,%edx > 1973: 31 c0 xor %eax,%eax > 1975: 83 c0 ff add $0xffffffff,%eax > 1978: 83 d2 ff adc $0xffffffff,%edx > 197b: 89 45 e0 mov %eax,-0x20(%ebp) > 197e: 89 55 e4 mov %edx,-0x1c(%ebp) > 1981: eb 0e jmp 1991 > else > mask =3D 0xFFFFFFFFFFFFFFFF; > 1983: c7 45 e0 ff ff ff ff movl $0xffffffff,-0x20(%ebp= ) > 198a: c7 45 e4 ff ff ff ff movl $0xffffffff,-0x1c(%ebp= ) Maybe I don't understand. You are saying you can fix the compiler warni= ng by=20 adding ULL to the constant. This is a simple patch and is a lot nicer t= han =09CFLAGS_i40e_lan_hmc.o +=3D -Wno-error Even if the asm code seems right, it would be more secure to remove thi= s=20 warning. PS: please try to configure your mailer to add citation marks. --=20 Thomas