2014-06-24 09:47, Chen, Jing D:
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> > 2014-06-24 13:22, Chen Jing D:
> > > +CFLAGS_i40e_lan_hmc.o += -Wno-error
> >
> > I know we shouldn't modify base drivers. But this one seems to be an
> > important error. In such case, we already modified base driver. Recently:
> > http://dpdk.org/ml/archives/dev/2014-June/003498.html
>
> I think it's different. The logic is right after adding the patch. Below is
> my finding.
> In this case, it met the error when compile on 32-bits OS. The message is :
>
> /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_pmd_i40e
> /i40e/i40e_lan_hmc.c: In function ?i40e_write_qword?:
> /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_pmd_i40
> e/i40e/i40e_lan_hmc.c:917: error: integer constant is too large for ?long?
> type
> /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_pmd_i40
> e/i40e/i40e_lan_hmc.c: In function ?i40e_read_qword?:
> /jenkins/workspace/DPDK_AUTO_IDT_VM_RHEL65_32_BUILD/DPDK/lib/librte_pmd_i40
> e/i40e/i40e_lan_hmc.c:1097: error: integer constant is too large for ?long?
> type
> I found the code that cause errors. 'mask' is 'uint64_t' type and is
> assigned to value 0Xffff_ffff_ffff_ffff. Compiler assumes the constant is
> 'int' type by default. If changed it to oxffff_ffff_ffff_ffffULL, the
> warning will be gone.
> if (ce_info->width < 64)
> mask = ((u64)1 << ce_info->width) - 1;
> else
> mask = 0xFFFFFFFFFFFFFFFF;
>
> besides that, I dis-assembler the code with the patch and get below segment.
> It seems right.
> 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 <i40e_write_qword+0x62>
> mask = ((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 <i40e_write_qword+0x54>
> 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 <i40e_write_qword+0x70>
> else
> mask = 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 warning by
adding ULL to the constant. This is a simple patch and is a lot nicer than
CFLAGS_i40e_lan_hmc.o += -Wno-error
Even if the asm code seems right, it would be more secure to remove this
warning.
PS: please try to configure your mailer to add citation marks.
--
Thomas
