From patchwork Thu Sep 12 14:41:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roese X-Patchwork-Id: 1161649 X-Patchwork-Delegate: hs@denx.de Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.denx.de (client-ip=81.169.180.215; helo=lists.denx.de; envelope-from=u-boot-bounces@lists.denx.de; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=denx.de Received: from lists.denx.de (dione.denx.de [81.169.180.215]) by ozlabs.org (Postfix) with ESMTP id 46ThKS3Q8Qz9s00 for ; Fri, 13 Sep 2019 00:41:16 +1000 (AEST) Received: by lists.denx.de (Postfix, from userid 105) id 15C2CC21E7D; Thu, 12 Sep 2019 14:41:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lists.denx.de X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=unavailable autolearn_force=no version=3.4.0 Received: from lists.denx.de (localhost [IPv6:::1]) by lists.denx.de (Postfix) with ESMTP id D460BC21DB5; Thu, 12 Sep 2019 14:41:09 +0000 (UTC) Received: by lists.denx.de (Postfix, from userid 105) id 15B37C21DED; Thu, 12 Sep 2019 14:41:08 +0000 (UTC) Received: from mx1.mailbox.org (mx1.mailbox.org [80.241.60.212]) by lists.denx.de (Postfix) with ESMTPS id 43F9BC21C2F for ; Thu, 12 Sep 2019 14:41:07 +0000 (UTC) Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:105:465:1:2:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx1.mailbox.org (Postfix) with ESMTPS id 162B0501D1; Thu, 12 Sep 2019 16:41:07 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter05.heinlein-hosting.de (spamfilter05.heinlein-hosting.de [80.241.56.123]) (amavisd-new, port 10030) with ESMTP id pTLnrISrXZnK; Thu, 12 Sep 2019 16:41:03 +0200 (CEST) From: Stefan Roese To: u-boot@lists.denx.de Date: Thu, 12 Sep 2019 16:41:01 +0200 Message-Id: <20190912144103.17261-1-sr@denx.de> MIME-Version: 1.0 Cc: Boris Brezillon , Quentin Schulz Subject: [U-Boot] [PATCH 1/3] ubi: provide a way to skip CRC checks X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.18 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" From: Quentin Schulz Some users of static UBI volumes implement their own integrity check, thus making the volume CRC check done at open time useless. For instance, this is the case when one use the ubiblock + dm-verity + squashfs combination, where dm-verity already checks integrity of the block device but this time at the block granularity instead of verifying the whole volume. Skipping this test drastically improves the boot-time. Adapted to U-Boot by Stefan Roese. Signed-off-by: Quentin Schulz Signed-off-by: Stefan Roese Cc: Quentin Schulz Cc: Boris Brezillon Cc: Heiko Schocher Reviewed-by: Heiko Schocher --- cmd/ubi.c | 25 +++++++++++++++++++------ drivers/mtd/ubi/kapi.c | 2 +- drivers/mtd/ubi/ubi-media.h | 6 ++++++ drivers/mtd/ubi/ubi.h | 4 ++++ drivers/mtd/ubi/vmt.c | 12 ++++++++++++ drivers/mtd/ubi/vtbl.c | 3 +++ include/mtd/ubi-user.h | 18 ++++++++++++++++-- 7 files changed, 61 insertions(+), 9 deletions(-) diff --git a/cmd/ubi.c b/cmd/ubi.c index ca5dc9021b..c857f07d93 100644 --- a/cmd/ubi.c +++ b/cmd/ubi.c @@ -146,7 +146,8 @@ bad: return err; } -static int ubi_create_vol(char *volume, int64_t size, int dynamic, int vol_id) +static int ubi_create_vol(char *volume, int64_t size, int dynamic, int vol_id, + bool skipcheck) { struct ubi_mkvol_req req; int err; @@ -163,7 +164,10 @@ static int ubi_create_vol(char *volume, int64_t size, int dynamic, int vol_id) strcpy(req.name, volume); req.name_len = strlen(volume); req.name[req.name_len] = '\0'; - req.padding1 = 0; + req.flags = 0; + if (skipcheck) + req.flags |= UBI_VOL_SKIP_CRC_CHECK_FLG; + /* It's duplicated at drivers/mtd/ubi/cdev.c */ err = verify_mkvol_req(ubi, &req); if (err) { @@ -469,6 +473,7 @@ static int do_ubi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { int64_t size = 0; ulong addr = 0; + bool skipcheck = false; if (argc < 2) return CMD_RET_USAGE; @@ -527,6 +532,12 @@ static int do_ubi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) /* Use maximum available size */ size = 0; + /* E.g., create volume with "skipcheck" bit set */ + if (argc == 7) { + skipcheck = strncmp(argv[6], "--skipcheck", 11) == 0; + argc--; + } + /* E.g., create volume size type vol_id */ if (argc == 6) { id = simple_strtoull(argv[5], NULL, 16); @@ -555,8 +566,10 @@ static int do_ubi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) printf("No size specified -> Using max size (%lld)\n", size); } /* E.g., create volume */ - if (argc == 3) - return ubi_create_vol(argv[2], size, dynamic, id); + if (argc == 3) { + return ubi_create_vol(argv[2], size, dynamic, id, + skipcheck); + } } if (strncmp(argv[1], "remove", 6) == 0) { @@ -623,7 +636,7 @@ static int do_ubi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) } U_BOOT_CMD( - ubi, 6, 1, do_ubi, + ubi, 7, 1, do_ubi, "ubi commands", "detach" " - detach ubi from a mtd partition\n" @@ -634,7 +647,7 @@ U_BOOT_CMD( " - Display volume and ubi layout information\n" "ubi check volumename" " - check if volumename exists\n" - "ubi create[vol] volume [size] [type] [id]\n" + "ubi create[vol] volume [size] [type] [id] [--skipcheck]\n" " - create volume name with size ('-' for maximum" " available size)\n" "ubi write[vol] address volume size" diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c index 2e171b0209..bcea71b1b2 100644 --- a/drivers/mtd/ubi/kapi.c +++ b/drivers/mtd/ubi/kapi.c @@ -196,7 +196,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode) desc->mode = mode; mutex_lock(&ubi->ckvol_mutex); - if (!vol->checked) { + if (!vol->checked && !vol->skip_check) { /* This is the first open - check the volume */ err = ubi_check_volume(ubi, vol_id); if (err < 0) { diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h index bd7a580961..4af85c4247 100644 --- a/drivers/mtd/ubi/ubi-media.h +++ b/drivers/mtd/ubi/ubi-media.h @@ -48,6 +48,11 @@ enum { * Volume flags used in the volume table record. * * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume + * @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at + * open time. Should only be set on volumes that + * are used by upper layers doing this kind of + * check. Main use-case for this flag is + * boot-time reduction * * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume * table. UBI automatically re-sizes the volume which has this flag and makes @@ -79,6 +84,7 @@ enum { */ enum { UBI_VTBL_AUTORESIZE_FLG = 0x01, + UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02, }; /* diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h index 918d03590c..f44960186b 100644 --- a/drivers/mtd/ubi/ubi.h +++ b/drivers/mtd/ubi/ubi.h @@ -293,6 +293,9 @@ struct ubi_fm_pool { * atomic LEB change * * @eba_tbl: EBA table of this volume (LEB->PEB mapping) + * @skip_check: %1 if CRC check of this static volume should be skipped. + * Directly reflects the presence of the + * %UBI_VTBL_SKIP_CRC_CHECK_FLG flag in the vtbl entry * @checked: %1 if this static volume was checked * @corrupted: %1 if the volume is corrupted (static volumes only) * @upd_marker: %1 if the update marker is set for this volume @@ -341,6 +344,7 @@ struct ubi_volume { void *upd_buf; int *eba_tbl; + unsigned int skip_check:1; unsigned int checked:1; unsigned int corrupted:1; unsigned int upd_marker:1; diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c index 94c8a98d47..a2ff1b5769 100644 --- a/drivers/mtd/ubi/vmt.c +++ b/drivers/mtd/ubi/vmt.c @@ -162,6 +162,9 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req) if (!vol) return -ENOMEM; + if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG) + vol->skip_check = 1; + spin_lock(&ubi->volumes_lock); if (vol_id == UBI_VOL_NUM_AUTO) { /* Find unused volume ID */ @@ -295,6 +298,10 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req) vtbl_rec.vol_type = UBI_VID_DYNAMIC; else vtbl_rec.vol_type = UBI_VID_STATIC; + + if (vol->skip_check) + vtbl_rec.flags |= UBI_VTBL_SKIP_CRC_CHECK_FLG; + memcpy(vtbl_rec.name, vol->name, vol->name_len); err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec); @@ -738,6 +745,11 @@ static int self_check_volume(struct ubi_device *ubi, int vol_id) ubi_err(ubi, "bad used_bytes"); goto fail; } + + if (vol->skip_check) { + ubi_err(ubi, "bad skip_check"); + goto fail; + } } else { if (vol->used_ebs < 0 || vol->used_ebs > vol->reserved_pebs) { ubi_err(ubi, "bad used_ebs"); diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c index fe96d3a894..fb535c1a87 100644 --- a/drivers/mtd/ubi/vtbl.c +++ b/drivers/mtd/ubi/vtbl.c @@ -554,6 +554,9 @@ static int init_volumes(struct ubi_device *ubi, vol->name[vol->name_len] = '\0'; vol->vol_id = i; + if (vtbl[i].flags & UBI_VTBL_SKIP_CRC_CHECK_FLG) + vol->skip_check = 1; + if (vtbl[i].flags & UBI_VTBL_AUTORESIZE_FLG) { /* Auto re-size flag may be set only for one volume */ if (ubi->autoresize_vol_id != -1) { diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h index cd81ef965c..8d472cc013 100644 --- a/include/mtd/ubi-user.h +++ b/include/mtd/ubi-user.h @@ -271,6 +271,20 @@ struct ubi_attach_req { __s8 padding[10]; }; +/* + * UBI volume flags. + * + * @UBI_VOL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at + * open time. Only valid for static volumes and + * should only be used if the volume user has a + * way to verify data integrity + */ +enum { + UBI_VOL_SKIP_CRC_CHECK_FLG = 0x1, +}; + +#define UBI_VOL_VALID_FLGS (UBI_VOL_SKIP_CRC_CHECK_FLG) + /** * struct ubi_mkvol_req - volume description data structure used in * volume creation requests. @@ -278,7 +292,7 @@ struct ubi_attach_req { * @alignment: volume alignment * @bytes: volume size in bytes * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME) - * @padding1: reserved for future, not used, has to be zeroed + * @flags: volume flags (%UBI_VOL_SKIP_CRC_CHECK_FLG) * @name_len: volume name length * @padding2: reserved for future, not used, has to be zeroed * @name: volume name @@ -307,7 +321,7 @@ struct ubi_mkvol_req { __s32 alignment; __s64 bytes; __s8 vol_type; - __s8 padding1; + __u8 flags; __s16 name_len; __s8 padding2[4]; char name[UBI_MAX_VOLUME_NAME + 1]; From patchwork Thu Sep 12 14:41:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roese X-Patchwork-Id: 1161650 X-Patchwork-Delegate: hs@denx.de Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.denx.de (client-ip=81.169.180.215; helo=lists.denx.de; envelope-from=u-boot-bounces@lists.denx.de; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=denx.de Received: from lists.denx.de (dione.denx.de [81.169.180.215]) by ozlabs.org (Postfix) with ESMTP id 46ThL95HdNz9s7T for ; Fri, 13 Sep 2019 00:41:53 +1000 (AEST) Received: by lists.denx.de (Postfix, from userid 105) id 51AF0C21E63; Thu, 12 Sep 2019 14:41:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lists.denx.de X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=unavailable autolearn_force=no version=3.4.0 Received: from lists.denx.de (localhost [IPv6:::1]) by lists.denx.de (Postfix) with ESMTP id 59958C21E39; Thu, 12 Sep 2019 14:41:10 +0000 (UTC) Received: by lists.denx.de (Postfix, from userid 105) id 368B3C21D8A; Thu, 12 Sep 2019 14:41:08 +0000 (UTC) Received: from mx2a.mailbox.org (mx2a.mailbox.org [80.241.60.219]) by lists.denx.de (Postfix) with ESMTPS id 73E2EC21D8A for ; Thu, 12 Sep 2019 14:41:07 +0000 (UTC) Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:105:465:1:2:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 324DDA1C30; Thu, 12 Sep 2019 16:41:07 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter03.heinlein-hosting.de (spamfilter03.heinlein-hosting.de [80.241.56.117]) (amavisd-new, port 10030) with ESMTP id SGx749SnldA3; Thu, 12 Sep 2019 16:41:04 +0200 (CEST) From: Stefan Roese To: u-boot@lists.denx.de Date: Thu, 12 Sep 2019 16:41:02 +0200 Message-Id: <20190912144103.17261-2-sr@denx.de> In-Reply-To: <20190912144103.17261-1-sr@denx.de> References: <20190912144103.17261-1-sr@denx.de> MIME-Version: 1.0 Cc: Boris Brezillon , Quentin Schulz Subject: [U-Boot] [PATCH 2/3] ubi: Print skip_check in ubi_dump_vol_info() X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.18 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" It might be interesting, if "skip_check" is set of not, so lets print this flag in ubi_dump_vol_info() as well. Signed-off-by: Stefan Roese Cc: Quentin Schulz Cc: Boris Brezillon Cc: Heiko Schocher Reviewed-by: Heiko Schocher --- drivers/mtd/ubi/debug.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c index 0a7427522c..f3d348da83 100644 --- a/drivers/mtd/ubi/debug.c +++ b/drivers/mtd/ubi/debug.c @@ -109,6 +109,7 @@ void ubi_dump_vol_info(const struct ubi_volume *vol) printf("\tlast_eb_bytes %d\n", vol->last_eb_bytes); printf("\tcorrupted %d\n", vol->corrupted); printf("\tupd_marker %d\n", vol->upd_marker); + printf("\tskip_check %d\n", vol->skip_check); if (vol->name_len <= UBI_VOL_NAME_MAX && strnlen(vol->name, vol->name_len + 1) == vol->name_len) { From patchwork Thu Sep 12 14:41:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roese X-Patchwork-Id: 1161651 X-Patchwork-Delegate: hs@denx.de Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.denx.de (client-ip=81.169.180.215; helo=lists.denx.de; envelope-from=u-boot-bounces@lists.denx.de; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=denx.de Received: from lists.denx.de (dione.denx.de [81.169.180.215]) by ozlabs.org (Postfix) with ESMTP id 46ThLN2sqBz9s00 for ; Fri, 13 Sep 2019 00:42:04 +1000 (AEST) Received: by lists.denx.de (Postfix, from userid 105) id B5397C21EC8; Thu, 12 Sep 2019 14:41:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lists.denx.de X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=unavailable autolearn_force=no version=3.4.0 Received: from lists.denx.de (localhost [IPv6:::1]) by lists.denx.de (Postfix) with ESMTP id 089CEC21E7E; Thu, 12 Sep 2019 14:41:11 +0000 (UTC) Received: by lists.denx.de (Postfix, from userid 105) id 45B4CC21DB5; Thu, 12 Sep 2019 14:41:09 +0000 (UTC) Received: from mx1.mailbox.org (mx1.mailbox.org [80.241.60.212]) by lists.denx.de (Postfix) with ESMTPS id AB668C21DB5 for ; Thu, 12 Sep 2019 14:41:07 +0000 (UTC) Received: from smtp2.mailbox.org (smtp2.mailbox.org [80.241.60.241]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx1.mailbox.org (Postfix) with ESMTPS id 97B234DE05; Thu, 12 Sep 2019 16:41:07 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id swQ7o64eHk97; Thu, 12 Sep 2019 16:41:04 +0200 (CEST) From: Stefan Roese To: u-boot@lists.denx.de Date: Thu, 12 Sep 2019 16:41:03 +0200 Message-Id: <20190912144103.17261-3-sr@denx.de> In-Reply-To: <20190912144103.17261-1-sr@denx.de> References: <20190912144103.17261-1-sr@denx.de> MIME-Version: 1.0 Cc: Boris Brezillon , Quentin Schulz Subject: [U-Boot] [PATCH 3/3] ubi: Add "skipcheck" command to set/clear this bit in the UBI volume hdr X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.18 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" U-Boot now supports the "skip_check" flag to optionally skip the CRC check at open time. Currently its only possible to set this bit upon UBI volume creation. But it might be very useful to also set this bit on already installed systems (e.g. field upgrade) to make also use of the boot-time decrease on those systems. This patch now adds a new "ubi" command "ubi skipcheck" to set or clear this bit in the UBI volume header: => ubi skipcheck rootfs0 on Setting skip_check on volume rootfs0 BTW: This saves approx. 10 seconds Linux bootup time on a MT7688 based target with 128MiB of SPI NAND. Signed-off-by: Stefan Roese Cc: Quentin Schulz Cc: Boris Brezillon Cc: Heiko Schocher Reviewed-by: Heiko Schocher --- cmd/ubi.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/cmd/ubi.c b/cmd/ubi.c index c857f07d93..42b5641b32 100644 --- a/cmd/ubi.c +++ b/cmd/ubi.c @@ -419,6 +419,30 @@ static int ubi_dev_scan(struct mtd_info *info, const char *vid_header_offset) return 0; } +static int ubi_set_skip_check(char *volume, bool skip_check) +{ + struct ubi_vtbl_record vtbl_rec; + struct ubi_volume *vol; + + vol = ubi_find_volume(volume); + if (vol == NULL) + return ENODEV; + + printf("%sing skip_check on volume %s\n", + skip_check ? "Sett" : "Clear", volume); + + vtbl_rec = ubi->vtbl[vol->vol_id]; + if (skip_check) { + vtbl_rec.flags |= UBI_VTBL_SKIP_CRC_CHECK_FLG; + vol->skip_check = 1; + } else { + vtbl_rec.flags &= ~UBI_VTBL_SKIP_CRC_CHECK_FLG; + vol->skip_check = 0; + } + + return ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec); +} + static int ubi_detach(void) { #ifdef CONFIG_CMD_UBIFS @@ -578,6 +602,14 @@ static int do_ubi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) return ubi_remove_vol(argv[2]); } + if (strncmp(argv[1], "skipcheck", 9) == 0) { + /* E.g., change skip_check flag */ + if (argc == 4) { + skipcheck = strncmp(argv[3], "on", 2) == 0; + return ubi_set_skip_check(argv[2], skipcheck); + } + } + if (strncmp(argv[1], "write", 5) == 0) { int ret; @@ -658,6 +690,8 @@ U_BOOT_CMD( " - Read volume to address with size\n" "ubi remove[vol] volume" " - Remove volume\n" + "ubi skipcheck volume on/off" + " - Set or clear skip_check flag in volume header\n" "[Legends]\n" " volume: character name\n" " size: specified in bytes\n"