From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42280) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKSdH-0000yl-P5 for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKSdG-0006aA-SA for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:31 -0400 From: Kevin Wolf Date: Tue, 5 Jul 2016 17:50:26 +0200 Message-Id: <1467733852-27097-18-git-send-email-kwolf@redhat.com> In-Reply-To: <1467733852-27097-1-git-send-email-kwolf@redhat.com> References: <1467733852-27097-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 17/43] block: Wording tweaks to write zeroes limits List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Eric Blake Improve the documentation of the write zeroes limits, to mention additional constraints that drivers should observe. Worth squashing into commit cf081fca, if that hadn't been pushed already :) Signed-off-by: Eric Blake Reviewed-by: Fam Zheng Signed-off-by: Kevin Wolf --- include/block/block_int.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/include/block/block_int.h b/include/block/block_int.h index 7d2b152..7a4a00f 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -331,11 +331,14 @@ typedef struct BlockLimits { int64_t discard_alignment; /* maximum number of bytes that can zeroized at once (since it is - * signed, it must be < 2G, if set) */ + * signed, it must be < 2G, if set), should be multiple of + * pwrite_zeroes_alignment. May be 0 if no inherent 32-bit limit */ int32_t max_pwrite_zeroes; /* optimal alignment for write zeroes requests in bytes, must be - * power of 2, and less than max_pwrite_zeroes if that is set */ + * power of 2, less than max_pwrite_zeroes if that is set, and + * multiple of bs->request_alignment. May be 0 if + * bs->request_alignment is good enough */ uint32_t pwrite_zeroes_alignment; /* optimal transfer length in bytes (must be power of 2, and -- 1.8.3.1