From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F53F1DDC38; Sun, 24 May 2026 01:44:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779587084; cv=none; b=Z94riM8F+LPS5pijWsPOy9Kv4IAe1wtlemT09eBkZMmxKCBBs2klcBShQaMkYGAYSwGYJJoG8lU02T0cUmR/BK9WrUj+zhGBk2va8kHBDCwiuU676dy0E3+kUjttMmZ2/ufFRtCMuhMaxbuE1hkRUpdonIEimEiTeu1HDIik8R8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779587084; c=relaxed/simple; bh=pASKiUhngDJqJtSseIMPQGmPi1FoocQ5F9U2lCmnwSk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=r2EHB1rX9LwD9VpLQlq/XL0OH65VyBPbs6IZKfDbvxBTZ+pYqMz2oru2ox9K29CvKchqOUfcZ6Ntw9rO8t7bSWZySz0ObPvSd23GIDLJb7D6Nxq98MT24oDMh2vo/ULurdJe2F8AAYvUo/12FJvucjFHHd4f7PRZybNWyctnsQo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nGYZ8pVN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nGYZ8pVN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 421521F000E9; Sun, 24 May 2026 01:44:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779587083; bh=SZeLFne5zONtUyedQld9JbP+mKovlG1YltZn9Usop30=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=nGYZ8pVNiq+nIsDyLYJVMennKi+iDJTU1vQv9gFiHMMWxw/upOyseuZ0PZreK6Miu np8untuxHjKw/kMYTLJByOva1KSTtGDQzGqizKLXAwBtQ2Mf9EfFgZrsVEpyX4gaox WvQV1/vV/r2XlkmRF8Oonm0FyCRCLUQ4gs8hLlwfWqkdpGSKcQr/xGVenDM/bZgs9r cDKW/hj1TQSx2g5MCkeb99cc/ynEpFgPxENkMIewTDJPhPynkiRfl5exqF8hpRBxOe ozHsN7xDcva48+XyGjqdqg/fiQr8YcZsXe3kFzWGghE0k0UYAelUErmkxuxCWp4o/+ X7wg+3urtOMoA== Date: Sun, 24 May 2026 10:44:39 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Theodore Ts'o , "Jason A . Donenfeld" , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [RFC PATCH 2/2] tracing: Record and show boot ID in last_boot_info Message-Id: <20260524104439.ec01284998cae6d4a5053e61@kernel.org> In-Reply-To: <20260521111630.1f558754@gandalf.local.home> References: <177937541909.2596845.17729857441826694760.stgit@mhiramat.tok.corp.google.com> <177937543666.2596845.9748178606108139386.stgit@mhiramat.tok.corp.google.com> <20260521111630.1f558754@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 21 May 2026 11:16:30 -0400 Steven Rostedt wrote: > On Thu, 21 May 2026 23:57:16 +0900 > "Masami Hiramatsu (Google)" wrote: > > > @@ -4804,6 +4806,7 @@ struct trace_mod_entry { > > struct trace_scratch { > > unsigned int clock_id; > > unsigned long text_addr; > > + u8 boot_id[UUID_SIZE]; > > unsigned long nr_entries; > > struct trace_mod_entry entries[]; > > }; > > I just don't like wasting scratch space if boot_id isn't defined. But I > can't figure out a way to optionally have it there without wasting space > anyway. Yeah, it needs to be placed in the scratch area or ring-buffer meta page. In most cases the boot_id is enabled (random subsystem seems to provide this UUID always), so it will be rarely waste of memory except CONFIG_SYSCTL=n. > > If the get_boot_id() is accepted by the random folks, then I'm fine with > this change. Yeah, BTW, Sashiko found this can be initialized before we get enough entropy for random seed. Maybe we need one more delay. Thank you, > > -- Steve -- Masami Hiramatsu (Google)