diff options
Diffstat (limited to 'Documentation/parisc')
| -rw-r--r-- | Documentation/parisc/00-INDEX | 6 | ||||
| -rw-r--r-- | Documentation/parisc/debugging | 39 | ||||
| -rw-r--r-- | Documentation/parisc/registers | 121 |
3 files changed, 0 insertions, 166 deletions
diff --git a/Documentation/parisc/00-INDEX b/Documentation/parisc/00-INDEX deleted file mode 100644 index cbd060961f4..00000000000 --- a/Documentation/parisc/00-INDEX +++ /dev/null @@ -1,6 +0,0 @@ -00-INDEX - - this file. -debugging - - some debugging hints for real-mode code -registers - - current/planned usage of registers diff --git a/Documentation/parisc/debugging b/Documentation/parisc/debugging deleted file mode 100644 index 7d75223fa18..00000000000 --- a/Documentation/parisc/debugging +++ /dev/null @@ -1,39 +0,0 @@ -okay, here are some hints for debugging the lower-level parts of -linux/parisc. - - -1. Absolute addresses - -A lot of the assembly code currently runs in real mode, which means -absolute addresses are used instead of virtual addresses as in the -rest of the kernel. To translate an absolute address to a virtual -address you can lookup in System.map, add __PAGE_OFFSET (0x10000000 -currently). - - -2. HPMCs - -When real-mode code tries to access non-existent memory, you'll get -an HPMC instead of a kernel oops. To debug an HPMC, try to find -the System Responder/Requestor addresses. The System Requestor -address should match (one of the) processor HPAs (high addresses in -the I/O range); the System Responder address is the address real-mode -code tried to access. - -Typical values for the System Responder address are addresses larger -than __PAGE_OFFSET (0x10000000) which mean a virtual address didn't -get translated to a physical address before real-mode code tried to -access it. - - -3. Q bit fun - -Certain, very critical code has to clear the Q bit in the PSW. What -happens when the Q bit is cleared is the CPU does not update the -registers interruption handlers read to find out where the machine -was interrupted - so if you get an interruption between the instruction -that clears the Q bit and the RFI that sets it again you don't know -where exactly it happened. If you're lucky the IAOQ will point to the -instruction that cleared the Q bit, if you're not it points anywhere -at all. Usually Q bit problems will show themselves in unexplainable -system hangs or running off the end of physical memory. diff --git a/Documentation/parisc/registers b/Documentation/parisc/registers deleted file mode 100644 index dd3caddd1ad..00000000000 --- a/Documentation/parisc/registers +++ /dev/null @@ -1,121 +0,0 @@ -Register Usage for Linux/PA-RISC - -[ an asterisk is used for planned usage which is currently unimplemented ] - - General Registers as specified by ABI - - Control Registers - -CR 0 (Recovery Counter) used for ptrace -CR 1-CR 7(undefined) unused -CR 8 (Protection ID) per-process value* -CR 9, 12, 13 (PIDS) unused -CR10 (CCR) lazy FPU saving* -CR11 as specified by ABI (SAR) -CR14 (interruption vector) initialized to fault_vector -CR15 (EIEM) initialized to all ones* -CR16 (Interval Timer) read for cycle count/write starts Interval Tmr -CR17-CR22 interruption parameters -CR19 Interrupt Instruction Register -CR20 Interrupt Space Register -CR21 Interrupt Offset Register -CR22 Interrupt PSW -CR23 (EIRR) read for pending interrupts/write clears bits -CR24 (TR 0) Kernel Space Page Directory Pointer -CR25 (TR 1) User Space Page Directory Pointer -CR26 (TR 2) not used -CR27 (TR 3) Thread descriptor pointer -CR28 (TR 4) not used -CR29 (TR 5) not used -CR30 (TR 6) current / 0 -CR31 (TR 7) Temporary register, used in various places - - Space Registers (kernel mode) - -SR0 temporary space register -SR4-SR7 set to 0 -SR1 temporary space register -SR2 kernel should not clobber this -SR3 used for userspace accesses (current process) - - Space Registers (user mode) - -SR0 temporary space register -SR1 temporary space register -SR2 holds space of linux gateway page -SR3 holds user address space value while in kernel -SR4-SR7 Defines short address space for user/kernel - - - Processor Status Word - -W (64-bit addresses) 0 -E (Little-endian) 0 -S (Secure Interval Timer) 0 -T (Taken Branch Trap) 0 -H (Higher-privilege trap) 0 -L (Lower-privilege trap) 0 -N (Nullify next instruction) used by C code -X (Data memory break disable) 0 -B (Taken Branch) used by C code -C (code address translation) 1, 0 while executing real-mode code -V (divide step correction) used by C code -M (HPMC mask) 0, 1 while executing HPMC handler* -C/B (carry/borrow bits) used by C code -O (ordered references) 1* -F (performance monitor) 0 -R (Recovery Counter trap) 0 -Q (collect interruption state) 1 (0 in code directly preceding an rfi) -P (Protection Identifiers) 1* -D (Data address translation) 1, 0 while executing real-mode code -I (external interrupt mask) used by cli()/sti() macros - - "Invisible" Registers - -PSW default W value 0 -PSW default E value 0 -Shadow Registers used by interruption handler code -TOC enable bit 1 - -========================================================================= -Register usage notes, originally from John Marvin, with some additional -notes from Randolph Chung. - -For the general registers: - -r1,r2,r19-r26,r28,r29 & r31 can be used without saving them first. And of -course, you need to save them if you care about them, before calling -another procedure. Some of the above registers do have special meanings -that you should be aware of: - - r1: The addil instruction is hardwired to place its result in r1, - so if you use that instruction be aware of that. - - r2: This is the return pointer. In general you don't want to - use this, since you need the pointer to get back to your - caller. However, it is grouped with this set of registers - since the caller can't rely on the value being the same - when you return, i.e. you can copy r2 to another register - and return through that register after trashing r2, and - that should not cause a problem for the calling routine. - - r19-r22: these are generally regarded as temporary registers. - Note that in 64 bit they are arg7-arg4. - - r23-r26: these are arg3-arg0, i.e. you can use them if you - don't care about the values that were passed in anymore. - - r28,r29: are ret0 and ret1. They are what you pass return values - in. r28 is the primary return. When returning small structures - r29 may also be used to pass data back to the caller. - - r30: stack pointer - - r31: the ble instruction puts the return pointer in here. - - -r3-r18,r27,r30 need to be saved and restored. r3-r18 are just - general purpose registers. r27 is the data pointer, and is - used to make references to global variables easier. r30 is - the stack pointer. - |