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mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none Received: from DM6PR15MB3289.namprd15.prod.outlook.com (2603:10b6:5:165::25) by DM6PR15MB3768.namprd15.prod.outlook.com (2603:10b6:5:2b0::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4042.16; Thu, 15 Apr 2021 20:57:21 +0000 Received: from DM6PR15MB3289.namprd15.prod.outlook.com ([fe80::f5c5:b681:9d22:70e8]) by DM6PR15MB3289.namprd15.prod.outlook.com ([fe80::f5c5:b681:9d22:70e8%4]) with mapi id 15.20.4042.016; Thu, 15 Apr 2021 20:57:21 +0000 Subject: Re: [PATCH bpf-next 12/17] libbpf: support extern resolution for BTF-defined maps in .maps section To: Andrii Nakryiko , Alexei Starovoitov CC: Andrii Nakryiko , bpf , Networking , Daniel Borkmann , Kernel Team References: <20210414200146.2663044-1-andrii@kernel.org> <20210414200146.2663044-13-andrii@kernel.org> <20210415020138.2dbcflpxq2zwu6b2@ast-mbp> From: Alexei Starovoitov Message-ID: Date: Thu, 15 Apr 2021 13:57:17 -0700 User-Agent: Mozilla/5.0 (Macintosh; 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Each extern > would need to specify all the attributes that should match the map > definition. That includes max_entries. That way the typedef struct { > ... } my_map_t re-use will work right out of the box. Later, if we see > this is not sufficient, we can start relaxing the rules. +1 >> >> btw for signed progs I'm thinking to allow override of max_entries only, >> since this attribute doesn't affect safety, correctness, behavior. >> Meaning max_entries will and will not be part of a signature at the same time. >> In other words it's necessary to support existing bcc/libbpf-tools. >> If we go with 'allow max_entries in extern' that would match that behavior. > > Ok, unless I misunderstood, allowing and checking all map attributes > as a starting point should work, right? yes. thanks!