From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42088) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1Yg5-0007DS-Cs for qemu-devel@nongnu.org; Tue, 23 Jul 2013 05:14:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V1Yg3-0001vI-Sj for qemu-devel@nongnu.org; Tue, 23 Jul 2013 05:14:41 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59962 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1Yg3-0001v9-Jd for qemu-devel@nongnu.org; Tue, 23 Jul 2013 05:14:39 -0400 Message-ID: <51EE497A.2080605@suse.de> Date: Tue, 23 Jul 2013 11:14:34 +0200 From: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= MIME-Version: 1.0 References: <1374510975-9896-1-git-send-email-afaerber@suse.de> <51EE23D0.2030708@redhat.com> In-Reply-To: <51EE23D0.2030708@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH qom-cpu] HACKING: Document vaddr type usage List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Peter Maydell , qemu-devel@nongnu.org Am 23.07.2013 08:33, schrieb Paolo Bonzini: > Il 22/07/2013 19:27, Peter Maydell ha scritto: >> On 22 July 2013 17:36, Andreas F=C3=A4rber wrote: >>> Signed-off-by: Andreas F=C3=A4rber >>> --- >>> HACKING | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/HACKING b/HACKING >>> index e73ac79..d9dbb46 100644 >>> --- a/HACKING >>> +++ b/HACKING >>> @@ -42,6 +42,7 @@ ram_addr_t. >>> >>> Use target_ulong (or abi_ulong) for CPU virtual addresses, however >>> devices should not need to use target_ulong. >>> +Use vaddr for CPU virtual addresses in target-independent code. >> >> Here's my suggestion for this paragraph (ie to replace >> both the "Use target_ulong..." and "Use vaddr" sentences >> above): >> >> =3D=3D=3Dbegin=3D=3D=3D >> For CPU virtual addresses there are several possible types. >> vaddr is the best type to use to hold a CPU virtual address >> in target-independent code, including most devices. It is >> guaranteed to be large enough to hold a virtual address for >> any target, and it does not change size from target to target. >> It is always unsigned. >> target_ulong is a type the size of a virtual address on the CPU; >> this means it may be 32 or 64 bits depending on which target >> is being built. It should therefore be used only in target >> specific code, and in some performance-critical built-per-target >> core code such as the TLB code. There is also a signed version, >> target_long. >> abi_ulong is for the *-user targets, and represents a type the >> size of 'void *' in that target's ABI. (This may not be the same >> as the size of a full CPU virtual address in the case of target >> ABIs which use 32 bit pointers on 64 bit CPUs, like sparc32plus.) >> Definitions of structures that must match the target's ABI >> must use this type for anything that on the target is defined >> to be an 'unsigned long' or a pointer type. There is also a >> signed version, abi_long. >> =3D=3D=3Dendit=3D=3D=3D >> >> (cc'ing Paolo to check I didn't mangle the abi_ulong/target_ulong >> distinction.) >=20 > Yes, it's fine. You might add that abi_short, abi_int, etc. also exist= , > and that they have the same alignment as short/int/etc in the target AB= I. >=20 > There is one nit: tn fact abi_ulong has the size of 'long'---which is > the same as 'void *', but only because our *-user targets are all ILP32 > or LP64. A hypotectical windows-user target would make abi_ullong the > size of 'void *'. Given the number of people that will read HACKING to that detail level, I hope you can send a follow-up patch to clarify that once merged. :) Andreas --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=C3=B6rffer; HRB 16746 AG N=C3=BC= rnberg