I'm seeing Cortex-A7 cycle-timing table here :
http://hardwarebug.org/2014/05/15/cortex-a7-instruction-cycle-timings/
For example,
VADD.F32 Dd, Dn, Dm takes 2 cycles
VADD.F32 Qd, Qn, Qm takes 4 cycles
same goes for VMUL..
Is this really the case…
I'm seeing Cortex-A7 cycle-timing table here :
http://hardwarebug.org/2014/05/15/cortex-a7-instruction-cycle-timings/
For example,
VADD.F32 Dd, Dn, Dm takes 2 cycles
VADD.F32 Qd, Qn, Qm takes 4 cycles
same goes for VMUL..
Is this really the case…
The registers in the instructions are usually 'named' Rn, Rm, Rd, ...
Is there some deeper meaning in the names?
Usually Rd seems to mean 'destination register'
Sometimes Rn is the only operand, sometimes it's Rm. Also the place in the instruction…
In quite many instruction descriptions it says:
if d == 15 then UNPREDICTABLE;
What does this mean?
Can the instruction really work in some unexpected way in each such case or what?
I guess if I use a bit-reversing instruction on PC I should expect that…
In some instruction descriptions there are calls to SignedSatQ (directly or indirectly).
The pseudocode for SignedSatQ:
(bits(N), boolean) SignedSatQ(integer i, integer N)
if i > 2^(N-1) - 1 then
result = 2^(N-1) - 1; saturated = TRUE;
elsif i < -(2…
Hi,
I was using following method to read clock in cortex-a15:
static void readticks(unsigned int *result)
{
struct timeval t;…
ARM friends,
I have done some research on software radio based on ZedBoard and AD-FMCOMMS1-EBZ.
ZedBoard is a development board which uses Xilinx Soc FPGA.
Xilinx Soc FPGA includes ARM Cortex A9 dual-core and Xilinx FPGA.
ZedBoard runs Ubuntu Linux operating…
Hi,
Where i can find step-by-step instruction how to init SMMU PA->IPA translation? (With procedure description)
(i checked ARM ® System Memory Management document, but i was not found exact instruction how to setup correct translation).
I have ARM…
In the SSAT instruction description it says:
ASR #32 Arithmetic right shift by 32 bits, permitted only for encoding A1.
Encoded as sh = 1, immsh = 0b00000.
What does that mean?
Isn't ASR #32 the same as ASR #31?
I understand that it shifts (with "sign…
Is there something special in the instructions ADD (SP plus register, ARM) and SUB (SP minus register)?
I didn't find anything different from the basic ADD (register) and SUB (register) except the documentation:
<Rd> The destination register…
First sorry my english writing level. :-)
In non-secure world using android system(linux kernel).
I use big.little core Cortex-A53, Cortex-A57
I was tested to 2case.
previous stage.
1. Linux allocation memory using(malloc or mmap)
Hi forks. I am a newbie engineer for arm-processor and I have a question about VMSAv7-32.
According to ARMv8 architecture manual, page 3592: arm processor can skip first level table if a first level table would contain only one entry..
How arm processor…
Hello, everyone.
Let me post a question regarding booting Linux on ARM FVP (with Cortex-A9 MPCore).
I'm setting up an experiment which uses TrustZone on ARM FVP. I'm not sure which
kernel to run in the secure world, but am sure to run Linux in Normal…
Hi Experts,
I'm developing some kind of Secure OS on A57/53 big.LITTLE SoC.
While multi-core testing, I'm facing some wired problem on my world shared memory mechanism.
When I run world shared memory test on a single core (using affinity), it works…
Is there a reason why banked registers SP and LR can't be accessed as r13_<mode> or r14_<mode>, but
one has to use SP_<mode> or LR_<mode> instead? It makes macros and inline assembly difficult.
In document (ARMv7-A/R ARM Issue…
I was wondering about LDRT when the operand is rrx'd. Which where does the carry-bit come from?
LDRT{<c>}{<q>} <Rt>, [<Rn>], +/-<Rm> {, <shift>}
RRX Rotate right one bit, with extend. Bit[0] is written to shifter_carry_out…
Hi,
I have used some 32-bit microprocessor cores (non-ARM), which has a long word-length accumulator for some DSP operations, to avoid over-flow etc. After I check A8 core document, it is a surprise that I do not see any about this specification. It looks…
Hi everyone!!
I am looking to work on some projects using ARM. I have completed a basic course on ARM M3/M4 (UT Austin 6.01x by Jon Valvano and Ramesh Yerraballi) online. Now, I want to learn advanced things, especially real-time applications. How should…
Hello experts,
I would like to ask the reason why the exception frame forms on PSP in the Cortex-M architecture.
My understanding is that MSP (Main Stack Pointer) is the interrupt stack pointer and PSP (Porcess Stack Pointer) is the normal (user) stack…
Hello,
I’m new to ARM architecture and was looking to get a better understanding of how it works. Most notably, the Cortex-A series and its DSP functionality.
When looking through the NEON SIMD page on ARM's webpage (NEON - ARM), it mentions that…
Hi,
I am working on bootloader porting to ARM v8 platform. I am facing a problem in enabling MMU in execution level-1 EL1.
I am not able to set sctlr_el1.M bit when ever i try to set this bit the instruction won't complete. I think it…
Hi ARM experts,
For shareability attribute, have some confusions:
1 For a memory location with cacheability attribute, does hardware do "flush" action after "writing" to push data to end if shareability attribute is also set. Otherwise…
Hi arm experts,
I wrote some simple C functions to check if the result of memcpy is expected after enable MMU and data cache on Cortex-A53. The assembly (got by disassembling with aarch64-none-elf-objdump) of the one of these functions…
Hello experts,
I feel I am an amateur.
I tried to work the performance monitor of Cortex-A9 but it did not work.
The followings are my codes.
Please tell me what was wrong.
mov r3, #0
mcr 15, 0, r3, cr9, cr12, {0} // PMCR PMU disable…Hi,
I have a beaglebone black and running a very basic app using starterware. As soon as the app starts executing i copy the CPSR values in memory. The value of CPSR is super surprising
6000019f
which means it is in SYS mode and IRQ, ABORT disabled and FIQ…