qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, qemu-arm@nongnu.org
Subject: [Qemu-devel] [PATCH v2 34/68] target/arm: Convert Clear-Exclusive, Barriers
Date: Mon, 19 Aug 2019 14:37:21 -0700	[thread overview]
Message-ID: <20190819213755.26175-35-richard.henderson@linaro.org> (raw)
In-Reply-To: <20190819213755.26175-1-richard.henderson@linaro.org>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/translate.c       | 122 +++++++++++++++--------------------
 target/arm/a32-uncond.decode |  10 +++
 target/arm/t32.decode        |  10 +++
 3 files changed, 73 insertions(+), 69 deletions(-)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index e268c5168d..6489bbc09c 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10038,6 +10038,58 @@ static bool trans_SRS(DisasContext *s, arg_SRS *a)
     return true;
 }
 
+/*
+ * Clear-Exclusive, Barriers
+ */
+
+static bool trans_CLREX(DisasContext *s, arg_CLREX *a)
+{
+    if (!ENABLE_ARCH_6K) {
+        return false;
+    }
+    gen_clrex(s);
+    return true;
+}
+
+static bool trans_DSB(DisasContext *s, arg_DSB *a)
+{
+    if (!s->thumb && !ENABLE_ARCH_7) {
+        return false;
+    }
+    tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
+    return true;
+}
+
+static bool trans_DMB(DisasContext *s, arg_DMB *a)
+{
+    return trans_DSB(s, NULL);
+}
+
+static bool trans_ISB(DisasContext *s, arg_ISB *a)
+{
+    /*
+     * We need to break the TB after this insn to execute
+     * self-modifying code correctly and also to take
+     * any pending interrupts immediately.
+     */
+    gen_goto_tb(s, 0, s->base.pc_next);
+    return true;
+}
+
+static bool trans_SB(DisasContext *s, arg_SB *a)
+{
+    if (!dc_isar_feature(aa32_sb, s)) {
+        return false;
+    }
+    /*
+     * TODO: There is no speculation barrier opcode
+     * for TCG; MB and end the TB instead.
+     */
+    tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
+    gen_goto_tb(s, 0, s->base.pc_next);
+    return true;
+}
+
 /*
  * Legacy decoder.
  */
@@ -10131,38 +10183,6 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
                 s->base.is_jmp = DISAS_UPDATE;
             }
             return;
-        } else if ((insn & 0x0fffff00) == 0x057ff000) {
-            switch ((insn >> 4) & 0xf) {
-            case 1: /* clrex */
-                ARCH(6K);
-                gen_clrex(s);
-                return;
-            case 4: /* dsb */
-            case 5: /* dmb */
-                ARCH(7);
-                tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
-                return;
-            case 6: /* isb */
-                /* We need to break the TB after this insn to execute
-                 * self-modifying code correctly and also to take
-                 * any pending interrupts immediately.
-                 */
-                gen_goto_tb(s, 0, s->base.pc_next);
-                return;
-            case 7: /* sb */
-                if ((insn & 0xf) || !dc_isar_feature(aa32_sb, s)) {
-                    goto illegal_op;
-                }
-                /*
-                 * TODO: There is no speculation barrier opcode
-                 * for TCG; MB and end the TB instead.
-                 */
-                tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
-                gen_goto_tb(s, 0, s->base.pc_next);
-                return;
-            default:
-                goto illegal_op;
-            }
         } else if ((insn & 0x0e000f00) == 0x0c000100) {
             if (arm_dc_feature(s, ARM_FEATURE_IWMMXT)) {
                 /* iWMMXt register transfer.  */
@@ -10623,43 +10643,7 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                             gen_set_psr_im(s, offset, 0, imm);
                         }
                         break;
-                    case 3: /* Special control operations.  */
-                        if (!arm_dc_feature(s, ARM_FEATURE_V7) &&
-                            !arm_dc_feature(s, ARM_FEATURE_M)) {
-                            goto illegal_op;
-                        }
-                        op = (insn >> 4) & 0xf;
-                        switch (op) {
-                        case 2: /* clrex */
-                            gen_clrex(s);
-                            break;
-                        case 4: /* dsb */
-                        case 5: /* dmb */
-                            tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
-                            break;
-                        case 6: /* isb */
-                            /* We need to break the TB after this insn
-                             * to execute self-modifying code correctly
-                             * and also to take any pending interrupts
-                             * immediately.
-                             */
-                            gen_goto_tb(s, 0, s->base.pc_next);
-                            break;
-                        case 7: /* sb */
-                            if ((insn & 0xf) || !dc_isar_feature(aa32_sb, s)) {
-                                goto illegal_op;
-                            }
-                            /*
-                             * TODO: There is no speculation barrier opcode
-                             * for TCG; MB and end the TB instead.
-                             */
-                            tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
-                            gen_goto_tb(s, 0, s->base.pc_next);
-                            break;
-                        default:
-                            goto illegal_op;
-                        }
-                        break;
+                    case 3: /* Special control operations, in decodetree */
                     case 4: /* bxj, in decodetree */
                         goto illegal_op;
                     case 5: /* Exception return.  */
diff --git a/target/arm/a32-uncond.decode b/target/arm/a32-uncond.decode
index 3b961233e5..b077958cec 100644
--- a/target/arm/a32-uncond.decode
+++ b/target/arm/a32-uncond.decode
@@ -22,6 +22,7 @@
 # All of those that have a COND field in insn[31:28] are in a32.decode
 #
 
+&empty           !extern
 &i               !extern imm
 
 # Branch with Link and Exchange
@@ -37,3 +38,12 @@ BLX_i            1111 101 . ........................          &i imm=%imm24h
 
 RFE              1111 100 pu:2 0 w:1 1 rn:4 0000 1010 0000 0000   &rfe
 SRS              1111 110 pu:2 1 w:1 0 1101 0000 0101 000 mode:5  &srs
+
+# Clear-Exclusive, Barriers
+
+# QEMU does not require the option field for the barriers.
+CLREX            1111 0101 0111 1111 1111 0000 0001 1111
+DSB              1111 0101 0111 1111 1111 0000 0100 ----
+DMB              1111 0101 0111 1111 1111 0000 0101 ----
+ISB              1111 0101 0111 1111 1111 0000 0110 ----
+SB               1111 0101 0111 1111 1111 0000 0111 0000
diff --git a/target/arm/t32.decode b/target/arm/t32.decode
index c8a8aeceee..18c268e712 100644
--- a/target/arm/t32.decode
+++ b/target/arm/t32.decode
@@ -305,6 +305,16 @@ CLZ              1111 1010 1011 ---- 1111 .... 1000 ....      @rdm
       # of the space is "reserved hint, behaves as nop".
       NOP        1111 0011 1010 1111 1000 0000 ---- ----
     }
+
+    # Miscelaneous control
+    {
+      CLREX      1111 0011 1011 1111 1000 1111 0010 1111
+      DSB        1111 0011 1011 1111 1000 1111 0100 ----
+      DMB        1111 0011 1011 1111 1000 1111 0101 ----
+      ISB        1111 0011 1011 1111 1000 1111 0110 ----
+      SB         1111 0011 1011 1111 1000 1111 0111 0000
+    }
+
     # Note that the v7m insn overlaps both the normal and banked insn.
     {
       MRS_bank   1111 0011 111 r:1 .... 1000 rd:4   001. 0000  \
-- 
2.17.1



  parent reply	other threads:[~2019-08-19 22:13 UTC|newest]

Thread overview: 167+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-19 21:36 [Qemu-devel] [PATCH v2 00/68] target/arm: Convert aa32 base isa to decodetree Richard Henderson
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 01/68] target/arm: Use store_reg_from_load in thumb2 code Richard Henderson
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 02/68] target/arm: Add stubs for aa32 decodetree Richard Henderson
2019-08-21 13:06   ` Philippe Mathieu-Daudé
2019-08-23 12:16   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 03/68] target/arm: Convert Data Processing (register) Richard Henderson
2019-08-22 16:00   ` Peter Maydell
2019-08-22 17:21     ` Richard Henderson
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 04/68] target/arm: Convert Data Processing (reg-shifted-reg) Richard Henderson
2019-08-23 12:17   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 05/68] target/arm: Convert Data Processing (immediate) Richard Henderson
2019-08-23 12:18   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 06/68] target/arm: Convert multiply and multiply accumulate Richard Henderson
2019-08-23 12:18   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 07/68] target/arm: Simplify UMAAL Richard Henderson
2019-08-23 12:20   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 08/68] target/arm: Convert Saturating addition and subtraction Richard Henderson
2019-08-21 13:15   ` Philippe Mathieu-Daudé
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 09/68] target/arm: Convert Halfword multiply and multiply accumulate Richard Henderson
2019-08-23 12:20   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 10/68] target/arm: Simplify op_smlaxxx for SMLAL* Richard Henderson
2019-08-23 12:21   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 11/68] target/arm: Simplify op_smlawx for SMLAW* Richard Henderson
2019-08-23 12:21   ` Peter Maydell
2019-08-19 21:36 ` [Qemu-devel] [PATCH v2 12/68] target/arm: Convert MSR (immediate) and hints Richard Henderson
2019-08-23 12:22   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 13/68] target/arm: Convert MRS/MSR (banked, register) Richard Henderson
2019-08-23 12:23   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 14/68] target/arm: Convert Cyclic Redundancy Check Richard Henderson
2019-08-23 12:23   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 15/68] target/arm: Convert BX, BXJ, BLX (register) Richard Henderson
2019-08-23 11:49   ` Peter Maydell
2019-08-23 14:22     ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 16/68] target/arm: Convert CLZ Richard Henderson
2019-08-23 11:52   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 17/68] target/arm: Convert ERET Richard Henderson
2019-08-23 12:25   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 18/68] target/arm: Convert the rest of A32 Miscelaneous instructions Richard Henderson
2019-08-23 12:03   ` Peter Maydell
2019-08-23 14:33     ` Richard Henderson
2019-08-27 10:32   ` Peter Maydell
2019-08-27 20:01     ` Richard Henderson
2019-08-27 22:29       ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 19/68] target/arm: Convert T32 ADDW/SUBW Richard Henderson
2019-08-23 13:04   ` Peter Maydell
2019-08-23 14:45     ` Richard Henderson
2019-08-23 14:47       ` Peter Maydell
2019-08-23 14:57         ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 20/68] target/arm: Convert load/store (register, immediate, literal) Richard Henderson
2019-08-23 14:54   ` Peter Maydell
2019-08-23 16:24     ` Richard Henderson
2019-08-27 12:27     ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 21/68] target/arm: Convert Synchronization primitives Richard Henderson
2019-08-23 15:28   ` Peter Maydell
2019-08-23 16:28     ` Richard Henderson
2019-08-27 10:44   ` Peter Maydell
2019-08-27 10:46     ` Peter Maydell
2019-08-27 11:10       ` Peter Maydell
2019-08-27 19:35         ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 22/68] target/arm: Convert USAD8, USADA8, SBFX, UBFX, BFC, BFI, UDF Richard Henderson
2019-08-23 15:39   ` Peter Maydell
2019-08-23 16:30     ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 23/68] target/arm: Convert Parallel addition and subtraction Richard Henderson
2019-08-23 15:53   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 24/68] target/arm: Convert Packing, unpacking, saturation, and reversal Richard Henderson
2019-08-23 16:46   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 25/68] target/arm: Convert Signed multiply, signed and unsigned divide Richard Henderson
2019-08-23 17:00   ` Peter Maydell
2019-08-23 17:15     ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 26/68] target/arm: Convert MOVW, MOVT Richard Henderson
2019-08-23 17:05   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 27/68] target/arm: Convert LDM, STM Richard Henderson
2019-08-23 17:27   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 28/68] target/arm: Diagnose writeback register in list for LDM for v7 Richard Henderson
2019-08-23 17:29   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 29/68] target/arm: Diagnose too few registers in list for LDM/STM Richard Henderson
2019-08-23 17:30   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 30/68] target/arm: Diagnose base == pc " Richard Henderson
2019-08-23 17:31   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 31/68] target/arm: Convert B, BL, BLX (immediate) Richard Henderson
2019-08-23 17:53   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 32/68] target/arm: Convert SVC Richard Henderson
2019-08-21 13:21   ` Philippe Mathieu-Daudé
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 33/68] target/arm: Convert RFE and SRS Richard Henderson
2019-08-25 15:28   ` Peter Maydell
2019-08-19 21:37 ` Richard Henderson [this message]
2019-08-25 15:52   ` [Qemu-devel] [PATCH v2 34/68] target/arm: Convert Clear-Exclusive, Barriers Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 35/68] target/arm: Convert CPS (privileged) Richard Henderson
2019-08-25 16:20   ` Peter Maydell
2019-08-25 17:28     ` Richard Henderson
2019-08-25 17:40       ` Richard Henderson
2019-08-25 20:43       ` Peter Maydell
2019-08-26  1:10         ` Richard Henderson
2019-08-26  1:36           ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 36/68] target/arm: Convert SETEND Richard Henderson
2019-08-21 13:22   ` Philippe Mathieu-Daudé
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 37/68] target/arm: Convert PLI, PLD, PLDW Richard Henderson
2019-08-21 13:23   ` Philippe Mathieu-Daudé
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 38/68] target/arm: Convert Unallocated memory hint Richard Henderson
2019-08-21 13:24   ` Philippe Mathieu-Daudé
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 39/68] target/arm: Convert Table Branch Richard Henderson
2019-08-25 16:27   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 40/68] target/arm: Convert SG Richard Henderson
2019-08-25 16:28   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 41/68] target/arm: Convert TT Richard Henderson
2019-08-25 16:33   ` Peter Maydell
2019-08-27 11:09   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 42/68] target/arm: Simplify disas_thumb2_insn Richard Henderson
2019-08-25 16:35   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 43/68] target/arm: Simplify disas_arm_insn Richard Henderson
2019-08-25 16:36   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 44/68] target/arm: Add skeleton for T16 decodetree Richard Henderson
2019-08-21 13:25   ` Philippe Mathieu-Daudé
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 45/68] target/arm: Convert T16 data-processing (two low regs) Richard Henderson
2019-08-25 21:06   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 46/68] target/arm: Convert T16 load/store (register offset) Richard Henderson
2019-08-25 21:13   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 47/68] target/arm: Convert T16 load/store (immediate offset) Richard Henderson
2019-08-25 21:22   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 48/68] target/arm: Convert T16 add pc/sp (immediate) Richard Henderson
2019-08-25 21:24   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 49/68] target/arm: Convert T16 load/store multiple Richard Henderson
2019-08-25 21:29   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 50/68] target/arm: Convert T16 add/sub (3 low, 2 low and imm) Richard Henderson
2019-08-25 21:33   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 51/68] target/arm: Convert T16 one low register and immediate Richard Henderson
2019-08-25 21:34   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 52/68] target/arm: Convert T16 branch and exchange Richard Henderson
2019-08-25 21:40   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 53/68] target/arm: Convert T16 add, compare, move (two high registers) Richard Henderson
2019-08-25 21:43   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 54/68] target/arm: Convert T16 adjust sp (immediate) Richard Henderson
2019-08-26 19:00   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 55/68] target/arm: Convert T16, extract Richard Henderson
2019-08-26 19:08   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 56/68] target/arm: Convert T16, Change processor state Richard Henderson
2019-08-26 19:25   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 57/68] target/arm: Convert T16, Reverse bytes Richard Henderson
2019-08-26 19:35   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 58/68] target/arm: Convert T16, nop hints Richard Henderson
2019-08-26 19:37   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 59/68] target/arm: Split gen_nop_hint Richard Henderson
2019-08-26 19:40   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 60/68] target/arm: Convert T16, push and pop Richard Henderson
2019-08-26 19:44   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 61/68] target/arm: Convert T16, Conditional branches, Supervisor call Richard Henderson
2019-08-26 19:52   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 62/68] target/arm: Convert T16, Miscellaneous 16-bit instructions Richard Henderson
2019-08-26 20:38   ` Peter Maydell
2019-08-26 23:47     ` Richard Henderson
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 63/68] target/arm: Convert T16, shift immediate Richard Henderson
2019-08-27  9:09   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 64/68] target/arm: Convert T16, load (literal) Richard Henderson
2019-08-27  9:11   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 65/68] target/arm: Convert T16, Unconditional branch Richard Henderson
2019-08-27  9:14   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 66/68] target/arm: Convert T16, long branches Richard Henderson
2019-08-27  9:34   ` Peter Maydell
2019-08-28  0:07     ` Richard Henderson
2019-09-03  8:23       ` Peter Maydell
2019-09-03  9:40       ` Aleksandar Markovic
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 67/68] target/arm: Clean up disas_thumb_insn Richard Henderson
2019-08-27  9:35   ` Peter Maydell
2019-08-19 21:37 ` [Qemu-devel] [PATCH v2 68/68] target/arm: Inline gen_bx_im into callers Richard Henderson
2019-08-27  9:39   ` Peter Maydell
2019-08-19 22:47 ` [Qemu-devel] [PATCH v2 00/68] target/arm: Convert aa32 base isa to decodetree no-reply
2019-08-27 12:28 ` Peter Maydell

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190819213755.26175-35-richard.henderson@linaro.org \
    --to=richard.henderson@linaro.org \
    --cc=peter.maydell@linaro.org \
    --cc=qemu-arm@nongnu.org \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).