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 Färber <afaer...@suse.de> wrote: >>> Signed-off-by: Andreas Färber <afaer...@suse.de> >>> --- >>> 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): >> >> ===begin=== >> 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. >> ===endit=== >> >> (cc'ing Paolo to check I didn't mangle the abi_ulong/target_ulong >> distinction.) > > 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 ABI. > > 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 -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
