Hi Julien, > -----Original Message----- > From: Julien Grall <[email protected]> > Sent: 2021年8月20日 16:24 > To: Wei Chen <[email protected]>; [email protected]; > [email protected]; [email protected] > Cc: Bertrand Marquis <[email protected]> > Subject: Re: [XEN RFC PATCH 07/40] xen/arm: use !CONFIG_NUMA to keep fake > NUMA API > > > > On 20/08/2021 03:08, Wei Chen wrote: > > Hi Julien, > > Hi Wei, > > > > >> -----Original Message----- > >> From: Julien Grall <[email protected]> > >> Sent: 2021年8月19日 21:34 > >> To: Wei Chen <[email protected]>; [email protected]; > >> [email protected]; [email protected] > >> Cc: Bertrand Marquis <[email protected]> > >> Subject: Re: [XEN RFC PATCH 07/40] xen/arm: use !CONFIG_NUMA to keep > fake > >> NUMA API > >> > >> Hi Wei, > >> > >> On 11/08/2021 11:23, Wei Chen wrote: > >>> Only Arm64 supports NUMA, the CONFIG_NUMA could not be > >>> enabled for Arm32. > >> > >> What do you mean by "could not be enabled"? > > > > I have not seen any Arm32 hardware support NUMA, so I think > > we don't need to support Arm32 NUMA. > > I understand that there may not be 32-bit platform with NUMA. And that's > fine stating that in the commit message. However... > > > In this case, this Kconfig > > option could not be enabled on Arm32. > > ... you continue to say "couldn't be enabled" without clarifying whether > this mean that the build will break or this was just not tested because > you don't have any platform.
Ok, I understand your concern. Yes, my words would lead to mis-understanding. If we make CONFIG_NUMA enabled in Arm32, it need Arm32 to implement some code to support NUMA common code. Otherwise the Arm32 build will failed. I have not tried to implement those code for Arm32. And I found there is no Arm32 machine support NUMA, so I wanted Arm32 to use fake NUMA API as before. > > To put it differently, the code for NUMA looks bitness neutral. So I > cannot really what what prevent us to potentially use it on Arm 32-bit. > Yes, you're right, it's neutral. But do we really need to add code to an ARCH that it may never use? And how can we test this code? Before this patch, I had checked Linux, and found that OF_NUMA only selected by Arm64 not Arm32. But if you feel the need to add to arm32, I have no problem with that. > > > >> > >>> Even in Arm64, users still can disable > >>> the CONFIG_NUMA through Kconfig option. In this case, keep > >>> current fake NUMA API, will make Arm code still can work > >>> with NUMA aware memory allocation and scheduler. > >>> > >>> Signed-off-by: Wei Chen <[email protected]> > >>> --- > >>> xen/include/asm-arm/numa.h | 4 ++++ > >>> 1 file changed, 4 insertions(+) > >>> > >>> diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h > >>> index 31a6de4e23..ab9c4a2448 100644 > >>> --- a/xen/include/asm-arm/numa.h > >>> +++ b/xen/include/asm-arm/numa.h > >>> @@ -5,6 +5,8 @@ > >>> > >>> typedef u8 nodeid_t; > >>> > >>> +#if !defined(CONFIG_NUMA) > >> > >> NIT: We tend to use #ifndef rather than #if !defined(...) > >> > > > > OK, I will change related changes in this series. > > > >>> + > >>> /* Fake one node for now. See also node_online_map. */ > >>> #define cpu_to_node(cpu) 0 > >>> #define node_to_cpumask(node) (cpu_online_map) > >>> @@ -25,6 +27,8 @@ extern mfn_t first_valid_mfn; > >>> #define node_start_pfn(nid) (mfn_x(first_valid_mfn)) > >>> #define __node_distance(a, b) (20) > >>> > >>> +#endif > >>> + > >>> #endif /* __ARCH_ARM_NUMA_H */ > >>> /* > >>> * Local variables: > >>> > >> > >> Cheers, > >> > >> -- > >> Julien Grall > > Cheers, > > -- > Julien Grall
