Paul Mackerras <pau...@samba.org> writes: > On Mon, Jul 30, 2012 at 04:52:19PM +0530, Aneesh Kumar K.V wrote: >> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> >> >> This update the proto-VSID and VSID scramble related information >> to be more generic by using names instead of current values. > > Comments below... > >> - * VSID allocation >> + * VSID allocation (256MB segment) >> * >> - * We first generate a 36-bit "proto-VSID". For kernel addresses this >> - * is equal to the ESID, for user addresses it is: >> - * (context << 15) | (esid & 0x7fff) >> + * We first generate a 38-bit "proto-VSID". For kernel addresses this >> + * is equal to the ESID | 1 << 37, for user addresses it is: >> + * (context << USER_ESID_BITS) | (esid & (1U << USER_ESID_BITS)) > ^^^^^^^^^^^^^^^^^^^^^^ > should be ((1U << USER_ESID_BITS) - 1) > >> * >> - * The two forms are distinguishable because the top bit is 0 for user >> - * addresses, whereas the top two bits are 1 for kernel addresses. >> - * Proto-VSIDs with the top two bits equal to 0b10 are reserved for >> - * now. >> + * This splits the proto-VSID into the below range >> + * 0 - (2^(CONTEXT_BITS + USER_ESID_BITS) - 1) : User proto-VSID range >> + * 2^(CONTEXT_BITS + USER_ESID_BITS) - 2^(VSID_BITS) : Kernel proto-VSID >> range > > Perhaps point out also that CONTEXT_BITS + USER_ESID_BITS == VSID_BITS - 1, > that is, you have assigned half of the space to user processes and half > to the kernel. >
updated >> -/* >> - * WARNING - If you change these you must make sure the asm >> - * implementations in slb_allocate (slb_low.S), do_stab_bolted >> - * (head.S) and ASM_VSID_SCRAMBLE (below) are changed accordingly. >> - */ > > Are you absolutely sure that nothing in the assembly code would need > to be changed if someone changed these definitions? > As a part of this patchset, i didn't touch any of these and the pathcset do change these values. -aneesh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
