On Feb 14, 2011, David Daney <ddaney@xxxxxxxxxxxxxxxxxx> wrote: > Current MIPS 32-bit ABIs (both o32 and n32) are restricted to 2GB of > user virtual memory space. This is due the way MIPS32 memory space is > segmented. Only the range from 0..2^31-1 is available. Pointer > values are always sign extended. > The proposed new ABI would only be available on MIPS64 platforms. It > would be identical to the current MIPS n32 ABI *except* that pointers > would be zero-extended rather than sign-extended when resident in > registers. FTR, I don't really know why my Yeeloong is limited to 31-bit addresses, and I kind of hoped an n32 userland would improve that WRT o32, without wasting memory with longer pointers like n64 would. So, sorry if this is a dumb question, but wouldn't it be much easier to keep on using sign-extended addresses, and just make sure the kernel never allocates a virtual memory range that crosses a sign-bit change, or whatever other reason there is for addresses to be limited to the positive 2GB range in n32? -- Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ You must be the change you wish to see in the world. -- Gandhi Be Free! -- http://FSFLA.org/ FSF Latin America board member Free Software Evangelist Red Hat Brazil Compiler Engineer
