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From: dthaler1968@googlemail.com
To: "'Yonghong Song'" <yonghong.song@linux.dev>,
	"'Jose E. Marchesi'" <jose.marchesi@oracle.com>,
	"'Dave Thaler'" <dthaler1968=40googlemail.com@dmarc.ietf.org>
Cc: <bpf@vger.kernel.org>, <bpf@ietf.org>
Subject: RE: [Bpf] [PATCH bpf-next v2] bpf, docs: Add callx instructions in new conformance group
Date: Mon, 12 Feb 2024 13:52:15 -0800	[thread overview]
Message-ID: <036301da5dfd$be7d1b30$3b775190$@gmail.com> (raw)
In-Reply-To: <b5072dfb-ab2b-40eb-891e-630a02c58fe8@linux.dev>

> -----Original Message-----
> From: Yonghong Song <yonghong.song@linux.dev>
> Sent: Monday, February 12, 2024 1:49 PM
> To: Jose E. Marchesi <jose.marchesi@oracle.com>; Dave Thaler
> <dthaler1968=40googlemail.com@dmarc.ietf.org>
> Cc: bpf@vger.kernel.org; bpf@ietf.org; Dave Thaler
> <dthaler1968@gmail.com>
> Subject: Re: [Bpf] [PATCH bpf-next v2] bpf, docs: Add callx instructions in new
> conformance group
> 
> 
> On 2/12/24 1:28 PM, Jose E. Marchesi wrote:
> >> +BPF_CALL  0x8    0x1  call PC += reg_val(imm)          BPF_JMP | BPF_X
> only, see `Program-local functions`_
> > If the instruction requires a register operand, why not using one of
> > the register fields?  Is there any reason for not doing that?
> 
> Talked to Alexei and we think using dst_reg for the register for callx insn is
> better. I will craft a llvm patch for this today. Thanks!

Why dst_reg instead of src_reg?
BPF_X is supposed to mean use src_reg.

But this thread is about reserving/documenting the existing practice,
since anyone trying to use it would run into interop issues because
of existing clang.   Should we document both and list one as deprecated?

Dave


WARNING: multiple messages have this Message-ID (diff)
From: dthaler1968=40googlemail.com@dmarc.ietf.org
To: "'Yonghong Song'" <yonghong.song@linux.dev>,
	"'Jose E. Marchesi'" <jose.marchesi@oracle.com>,
	"'Dave Thaler'" <dthaler1968=40googlemail.com@dmarc.ietf.org>
Cc: <bpf@vger.kernel.org>, <bpf@ietf.org>
Subject: Re: [Bpf] [PATCH bpf-next v2] bpf, docs: Add callx instructions in new conformance group
Date: Mon, 12 Feb 2024 13:52:15 -0800	[thread overview]
Message-ID: <036301da5dfd$be7d1b30$3b775190$@gmail.com> (raw)
Message-ID: <20240212215215.K8wKAzCGd_KlyUb7szlmX4B51JXIa3KwxjFop4KtGZo@z> (raw)
In-Reply-To: <b5072dfb-ab2b-40eb-891e-630a02c58fe8@linux.dev>

> -----Original Message-----
> From: Yonghong Song <yonghong.song@linux.dev>
> Sent: Monday, February 12, 2024 1:49 PM
> To: Jose E. Marchesi <jose.marchesi@oracle.com>; Dave Thaler
> <dthaler1968=40googlemail.com@dmarc.ietf.org>
> Cc: bpf@vger.kernel.org; bpf@ietf.org; Dave Thaler
> <dthaler1968@gmail.com>
> Subject: Re: [Bpf] [PATCH bpf-next v2] bpf, docs: Add callx instructions in new
> conformance group
> 
> 
> On 2/12/24 1:28 PM, Jose E. Marchesi wrote:
> >> +BPF_CALL  0x8    0x1  call PC += reg_val(imm)          BPF_JMP | BPF_X
> only, see `Program-local functions`_
> > If the instruction requires a register operand, why not using one of
> > the register fields?  Is there any reason for not doing that?
> 
> Talked to Alexei and we think using dst_reg for the register for callx insn is
> better. I will craft a llvm patch for this today. Thanks!

Why dst_reg instead of src_reg?
BPF_X is supposed to mean use src_reg.

But this thread is about reserving/documenting the existing practice,
since anyone trying to use it would run into interop issues because
of existing clang.   Should we document both and list one as deprecated?

Dave

-- 
Bpf mailing list
Bpf@ietf.org
https://www.ietf.org/mailman/listinfo/bpf

  parent reply	other threads:[~2024-02-12 21:52 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-12 21:13 [PATCH bpf-next v2] bpf, docs: Add callx instructions in new conformance group Dave Thaler
2024-02-12 21:13 ` [Bpf] " Dave Thaler
2024-02-12 21:21 ` David Vernet
2024-02-12 21:21   ` David Vernet
2024-02-12 21:28 ` Jose E. Marchesi
2024-02-12 21:28   ` Jose E. Marchesi
2024-02-12 21:46   ` dthaler1968
2024-02-12 21:46     ` dthaler1968=40googlemail.com
2024-02-12 21:49   ` Yonghong Song
2024-02-12 21:49     ` Yonghong Song
2024-02-12 21:52     ` dthaler1968 [this message]
2024-02-12 21:52       ` dthaler1968=40googlemail.com
2024-02-12 22:48       ` Yonghong Song
2024-02-12 22:48         ` Yonghong Song
2024-02-13  1:18         ` dthaler1968
2024-02-13  1:18           ` dthaler1968=40googlemail.com
2024-02-13  1:23           ` Yonghong Song
2024-02-13  1:23             ` Yonghong Song
2024-02-13  6:11         ` Jose E. Marchesi
2024-02-13  6:11           ` Jose E. Marchesi

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