diff options
Diffstat (limited to 'target-alpha/cpu.h')
| -rw-r--r-- | target-alpha/cpu.h | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/target-alpha/cpu.h b/target-alpha/cpu.h index dcdd0416bd..871d9baa35 100644 --- a/target-alpha/cpu.h +++ b/target-alpha/cpu.h @@ -201,7 +201,7 @@ enum { /* MMU modes definitions */ -/* Alpha has 5 MMU modes: PALcode, kernel, executive, supervisor, and user. +/* Alpha has 5 MMU modes: PALcode, Kernel, Executive, Supervisor, and User. The Unix PALcode only exposes the kernel and user modes; presumably executive and supervisor are used by VMS. @@ -209,22 +209,18 @@ enum { there are PALmode instructions that can access data via physical mode or via an os-installed "alternate mode", which is one of the 4 above. - QEMU does not currently properly distinguish between code/data when - looking up addresses. To avoid having to address this issue, our - emulated PALcode will cheat and use the KSEG mapping for its code+data - rather than physical addresses. + That said, we're only emulating Unix PALcode, and not attempting VMS, + so we don't need to implement Executive and Supervisor. QEMU's own + PALcode cheats and usees the KSEG mapping for its code+data rather than + physical addresses. */ - Moreover, we're only emulating Unix PALcode, and not attempting VMS. - - All of which allows us to drop all but kernel and user modes. - Elide the unused MMU modes to save space. */ - -#define NB_MMU_MODES 2 +#define NB_MMU_MODES 3 #define MMU_MODE0_SUFFIX _kernel #define MMU_MODE1_SUFFIX _user #define MMU_KERNEL_IDX 0 #define MMU_USER_IDX 1 +#define MMU_PHYS_IDX 2 typedef struct CPUAlphaState CPUAlphaState; |