828 lines
18 KiB
ReStructuredText
828 lines
18 KiB
ReStructuredText
===============================================
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ETMv4 sysfs linux driver programming reference.
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===============================================
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:Author: Mike Leach <mike.leach@linaro.org>
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:Date: October 11th, 2019
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Supplement to existing ETMv4 driver documentation.
|
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|
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Sysfs files and directories
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---------------------------
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Root: ``/sys/bus/coresight/devices/etm<N>``
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The following paragraphs explain the association between sysfs files and the
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ETMv4 registers that they effect. Note the register names are given without
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the ‘TRC’ prefix.
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----
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:File: ``mode`` (rw)
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:Trace Registers: {CONFIGR + others}
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:Notes:
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Bit select trace features. See ‘mode’ section below. Bits
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in this will cause equivalent programming of trace config and
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other registers to enable the features requested.
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:Syntax & eg:
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``echo bitfield > mode``
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bitfield up to 32 bits setting trace features.
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:Example:
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``$> echo 0x012 > mode``
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----
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:File: ``reset`` (wo)
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:Trace Registers: All
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:Notes:
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Reset all programming to trace nothing / no logic programmed.
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:Syntax:
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``echo 1 > reset``
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----
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:File: ``enable_source`` (wo)
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:Trace Registers: PRGCTLR, All hardware regs.
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:Notes:
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- > 0 : Programs up the hardware with the current values held in the driver
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and enables trace.
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- = 0 : disable trace hardware.
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:Syntax:
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``echo 1 > enable_source``
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----
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:File: ``cpu`` (ro)
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:Trace Registers: None.
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:Notes:
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CPU ID that this ETM is attached to.
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:Example:
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``$> cat cpu``
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``$> 0``
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----
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:File: ``ts_source`` (ro)
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:Trace Registers: None.
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:Notes:
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When FEAT_TRF is implemented, value of TRFCR_ELx.TS used for trace session. Otherwise -1
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indicates an unknown time source. Check trcidr0.tssize to see if a global timestamp is
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available.
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:Example:
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``$> cat ts_source``
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``$> 1``
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----
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:File: ``addr_idx`` (rw)
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:Trace Registers: None.
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:Notes:
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Virtual register to index address comparator and range
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features. Set index for first of the pair in a range.
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:Syntax:
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``echo idx > addr_idx``
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Where idx < nr_addr_cmp x 2
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----
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:File: ``addr_range`` (rw)
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:Trace Registers: ACVR[idx, idx+1], VIIECTLR
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:Notes:
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Pair of addresses for a range selected by addr_idx. Include
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/ exclude according to the optional parameter, or if omitted
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uses the current ‘mode’ setting. Select comparator range in
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control register. Error if index is odd value.
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:Depends: ``mode, addr_idx``
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:Syntax:
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``echo addr1 addr2 [exclude] > addr_range``
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Where addr1 and addr2 define the range and addr1 < addr2.
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Optional exclude value:-
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- 0 for include
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- 1 for exclude.
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:Example:
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``$> echo 0x0000 0x2000 0 > addr_range``
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----
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:File: ``addr_single`` (rw)
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:Trace Registers: ACVR[idx]
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:Notes:
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Set a single address comparator according to addr_idx. This
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is used if the address comparator is used as part of event
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generation logic etc.
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:Depends: ``addr_idx``
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:Syntax:
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``echo addr1 > addr_single``
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----
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:File: ``addr_start`` (rw)
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:Trace Registers: ACVR[idx], VISSCTLR
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:Notes:
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Set a trace start address comparator according to addr_idx.
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Select comparator in control register.
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:Depends: ``addr_idx``
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:Syntax:
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``echo addr1 > addr_start``
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----
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:File: ``addr_stop`` (rw)
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:Trace Registers: ACVR[idx], VISSCTLR
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:Notes:
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Set a trace stop address comparator according to addr_idx.
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Select comparator in control register.
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:Depends: ``addr_idx``
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:Syntax:
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``echo addr1 > addr_stop``
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----
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:File: ``addr_context`` (rw)
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:Trace Registers: ACATR[idx,{6:4}]
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:Notes:
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Link context ID comparator to address comparator addr_idx
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:Depends: ``addr_idx``
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:Syntax:
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``echo ctxt_idx > addr_context``
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Where ctxt_idx is the index of the linked context id / vmid
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comparator.
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----
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:File: ``addr_ctxtype`` (rw)
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:Trace Registers: ACATR[idx,{3:2}]
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:Notes:
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Input value string. Set type for linked context ID comparator
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:Depends: ``addr_idx``
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:Syntax:
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``echo type > addr_ctxtype``
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Type one of {all, vmid, ctxid, none}
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:Example:
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``$> echo ctxid > addr_ctxtype``
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----
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:File: ``addr_exlevel_s_ns`` (rw)
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:Trace Registers: ACATR[idx,{14:8}]
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:Notes:
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Set the ELx secure and non-secure matching bits for the
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selected address comparator
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:Depends: ``addr_idx``
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:Syntax:
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``echo val > addr_exlevel_s_ns``
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val is a 7 bit value for exception levels to exclude. Input
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value shifted to correct bits in register.
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:Example:
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``$> echo 0x4F > addr_exlevel_s_ns``
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----
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:File: ``addr_instdatatype`` (rw)
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:Trace Registers: ACATR[idx,{1:0}]
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:Notes:
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Set the comparator address type for matching. Driver only
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supports setting instruction address type.
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:Depends: ``addr_idx``
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----
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:File: ``addr_cmp_view`` (ro)
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:Trace Registers: ACVR[idx, idx+1], ACATR[idx], VIIECTLR
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:Notes:
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Read the currently selected address comparator. If part of
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address range then display both addresses.
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:Depends: ``addr_idx``
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:Syntax:
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``cat addr_cmp_view``
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:Example:
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``$> cat addr_cmp_view``
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``addr_cmp[0] range 0x0 0xffffffffffffffff include ctrl(0x4b00)``
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----
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:File: ``nr_addr_cmp`` (ro)
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:Trace Registers: From IDR4
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:Notes:
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Number of address comparator pairs
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||
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----
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:File: ``sshot_idx`` (rw)
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:Trace Registers: None
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:Notes:
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Select single shot register set.
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----
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:File: ``sshot_ctrl`` (rw)
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:Trace Registers: SSCCR[idx]
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:Notes:
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Access a single shot comparator control register.
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:Depends: ``sshot_idx``
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:Syntax:
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``echo val > sshot_ctrl``
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Writes val into the selected control register.
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----
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:File: ``sshot_status`` (ro)
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:Trace Registers: SSCSR[idx]
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:Notes:
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Read a single shot comparator status register
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:Depends: ``sshot_idx``
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:Syntax:
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``cat sshot_status``
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Read status.
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:Example:
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``$> cat sshot_status``
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``0x1``
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----
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:File: ``sshot_pe_ctrl`` (rw)
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:Trace Registers: SSPCICR[idx]
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:Notes:
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Access a single shot PE comparator input control register.
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:Depends: ``sshot_idx``
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:Syntax:
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``echo val > sshot_pe_ctrl``
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Writes val into the selected control register.
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----
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:File: ``ns_exlevel_vinst`` (rw)
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:Trace Registers: VICTLR{23:20}
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:Notes:
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Program non-secure exception level filters. Set / clear NS
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exception filter bits. Setting ‘1’ excludes trace from the
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exception level.
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:Syntax:
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``echo bitfield > ns_exlevel_viinst``
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Where bitfield contains bits to set clear for EL0 to EL2
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:Example:
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``%> echo 0x4 > ns_exlevel_viinst``
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Excludes EL2 NS trace.
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||
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----
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:File: ``vinst_pe_cmp_start_stop`` (rw)
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:Trace Registers: VIPCSSCTLR
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:Notes:
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Access PE start stop comparator input control registers
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----
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:File: ``bb_ctrl`` (rw)
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:Trace Registers: BBCTLR
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:Notes:
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Define ranges that Branch Broadcast will operate in.
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Default (0x0) is all addresses.
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||
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:Depends: BB enabled.
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----
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:File: ``cyc_threshold`` (rw)
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:Trace Registers: CCCTLR
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:Notes:
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Set the threshold for which cycle counts will be emitted.
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Error if attempt to set below minimum defined in IDR3, masked
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to width of valid bits.
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:Depends: CC enabled.
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||
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----
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:File: ``syncfreq`` (rw)
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:Trace Registers: SYNCPR
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:Notes:
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Set trace synchronisation period. Power of 2 value, 0 (off)
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or 8-20. Driver defaults to 12 (every 4096 bytes).
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----
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:File: ``cntr_idx`` (rw)
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:Trace Registers: none
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||
:Notes:
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Select the counter to access
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||
:Syntax:
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``echo idx > cntr_idx``
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Where idx < nr_cntr
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----
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||
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:File: ``cntr_ctrl`` (rw)
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:Trace Registers: CNTCTLR[idx]
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:Notes:
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Set counter control value.
|
||
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||
:Depends: ``cntr_idx``
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||
:Syntax:
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||
``echo val > cntr_ctrl``
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Where val is per ETMv4 spec.
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||
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----
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||
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:File: ``cntrldvr`` (rw)
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:Trace Registers: CNTRLDVR[idx]
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:Notes:
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Set counter reload value.
|
||
|
||
:Depends: ``cntr_idx``
|
||
:Syntax:
|
||
``echo val > cntrldvr``
|
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|
||
Where val is per ETMv4 spec.
|
||
|
||
----
|
||
|
||
:File: ``nr_cntr`` (ro)
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||
:Trace Registers: From IDR5
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||
|
||
:Notes:
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||
Number of counters implemented.
|
||
|
||
----
|
||
|
||
:File: ``ctxid_idx`` (rw)
|
||
:Trace Registers: None
|
||
:Notes:
|
||
Select the context ID comparator to access
|
||
|
||
:Syntax:
|
||
``echo idx > ctxid_idx``
|
||
|
||
Where idx < numcidc
|
||
|
||
----
|
||
|
||
:File: ``ctxid_pid`` (rw)
|
||
:Trace Registers: CIDCVR[idx]
|
||
:Notes:
|
||
Set the context ID comparator value
|
||
|
||
:Depends: ``ctxid_idx``
|
||
|
||
----
|
||
|
||
:File: ``ctxid_masks`` (rw)
|
||
:Trace Registers: CIDCCTLR0, CIDCCTLR1, CIDCVR<0-7>
|
||
:Notes:
|
||
Pair of values to set the byte masks for 1-8 context ID
|
||
comparators. Automatically clears masked bytes to 0 in CID
|
||
value registers.
|
||
|
||
:Syntax:
|
||
``echo m3m2m1m0 [m7m6m5m4] > ctxid_masks``
|
||
|
||
32 bit values made up of mask bytes, where mN represents a
|
||
byte mask value for Context ID comparator N.
|
||
|
||
Second value not required on systems that have fewer than 4
|
||
context ID comparators
|
||
|
||
----
|
||
|
||
:File: ``numcidc`` (ro)
|
||
:Trace Registers: From IDR4
|
||
:Notes:
|
||
Number of Context ID comparators
|
||
|
||
----
|
||
|
||
:File: ``vmid_idx`` (rw)
|
||
:Trace Registers: None
|
||
:Notes:
|
||
Select the VM ID comparator to access.
|
||
|
||
:Syntax:
|
||
``echo idx > vmid_idx``
|
||
|
||
Where idx < numvmidc
|
||
|
||
----
|
||
|
||
:File: ``vmid_val`` (rw)
|
||
:Trace Registers: VMIDCVR[idx]
|
||
:Notes:
|
||
Set the VM ID comparator value
|
||
|
||
:Depends: ``vmid_idx``
|
||
|
||
----
|
||
|
||
:File: ``vmid_masks`` (rw)
|
||
:Trace Registers: VMIDCCTLR0, VMIDCCTLR1, VMIDCVR<0-7>
|
||
:Notes:
|
||
Pair of values to set the byte masks for 1-8 VM ID comparators.
|
||
Automatically clears masked bytes to 0 in VMID value registers.
|
||
|
||
:Syntax:
|
||
``echo m3m2m1m0 [m7m6m5m4] > vmid_masks``
|
||
|
||
Where mN represents a byte mask value for VMID comparator N.
|
||
Second value not required on systems that have fewer than 4
|
||
VMID comparators.
|
||
|
||
----
|
||
|
||
:File: ``numvmidc`` (ro)
|
||
:Trace Registers: From IDR4
|
||
:Notes:
|
||
Number of VMID comparators
|
||
|
||
----
|
||
|
||
:File: ``res_idx`` (rw)
|
||
:Trace Registers: None.
|
||
:Notes:
|
||
Select the resource selector control to access. Must be 2 or
|
||
higher as selectors 0 and 1 are hardwired.
|
||
|
||
:Syntax:
|
||
``echo idx > res_idx``
|
||
|
||
Where 2 <= idx < nr_resource x 2
|
||
|
||
----
|
||
|
||
:File: ``res_ctrl`` (rw)
|
||
:Trace Registers: RSCTLR[idx]
|
||
:Notes:
|
||
Set resource selector control value. Value per ETMv4 spec.
|
||
|
||
:Depends: ``res_idx``
|
||
:Syntax:
|
||
``echo val > res_cntr``
|
||
|
||
Where val is per ETMv4 spec.
|
||
|
||
----
|
||
|
||
:File: ``nr_resource`` (ro)
|
||
:Trace Registers: From IDR4
|
||
:Notes:
|
||
Number of resource selector pairs
|
||
|
||
----
|
||
|
||
:File: ``event`` (rw)
|
||
:Trace Registers: EVENTCTRL0R
|
||
:Notes:
|
||
Set up to 4 implemented event fields.
|
||
|
||
:Syntax:
|
||
``echo ev3ev2ev1ev0 > event``
|
||
|
||
Where evN is an 8 bit event field. Up to 4 event fields make up the
|
||
32-bit input value. Number of valid fields is implementation dependent,
|
||
defined in IDR0.
|
||
|
||
----
|
||
|
||
:File: ``event_instren`` (rw)
|
||
:Trace Registers: EVENTCTRL1R
|
||
:Notes:
|
||
Choose events which insert event packets into trace stream.
|
||
|
||
:Depends: EVENTCTRL0R
|
||
:Syntax:
|
||
``echo bitfield > event_instren``
|
||
|
||
Where bitfield is up to 4 bits according to number of event fields.
|
||
|
||
----
|
||
|
||
:File: ``event_ts`` (rw)
|
||
:Trace Registers: TSCTLR
|
||
:Notes:
|
||
Set the event that will generate timestamp requests.
|
||
|
||
:Depends: ``TS activated``
|
||
:Syntax:
|
||
``echo evfield > event_ts``
|
||
|
||
Where evfield is an 8 bit event selector.
|
||
|
||
----
|
||
|
||
:File: ``seq_idx`` (rw)
|
||
:Trace Registers: None
|
||
:Notes:
|
||
Sequencer event register select - 0 to 2
|
||
|
||
----
|
||
|
||
:File: ``seq_state`` (rw)
|
||
:Trace Registers: SEQSTR
|
||
:Notes:
|
||
Sequencer current state - 0 to 3.
|
||
|
||
----
|
||
|
||
:File: ``seq_event`` (rw)
|
||
:Trace Registers: SEQEVR[idx]
|
||
:Notes:
|
||
State transition event registers
|
||
|
||
:Depends: ``seq_idx``
|
||
:Syntax:
|
||
``echo evBevF > seq_event``
|
||
|
||
Where evBevF is a 16 bit value made up of two event selectors,
|
||
|
||
- evB : back
|
||
- evF : forwards.
|
||
|
||
----
|
||
|
||
:File: ``seq_reset_event`` (rw)
|
||
:Trace Registers: SEQRSTEVR
|
||
:Notes:
|
||
Sequencer reset event
|
||
|
||
:Syntax:
|
||
``echo evfield > seq_reset_event``
|
||
|
||
Where evfield is an 8 bit event selector.
|
||
|
||
----
|
||
|
||
:File: ``nrseqstate`` (ro)
|
||
:Trace Registers: From IDR5
|
||
:Notes:
|
||
Number of sequencer states (0 or 4)
|
||
|
||
----
|
||
|
||
:File: ``nr_pe_cmp`` (ro)
|
||
:Trace Registers: From IDR4
|
||
:Notes:
|
||
Number of PE comparator inputs
|
||
|
||
----
|
||
|
||
:File: ``nr_ext_inp`` (ro)
|
||
:Trace Registers: From IDR5
|
||
:Notes:
|
||
Number of external inputs
|
||
|
||
----
|
||
|
||
:File: ``nr_ss_cmp`` (ro)
|
||
:Trace Registers: From IDR4
|
||
:Notes:
|
||
Number of Single Shot control registers
|
||
|
||
----
|
||
|
||
*Note:* When programming any address comparator the driver will tag the
|
||
comparator with a type used - i.e. RANGE, SINGLE, START, STOP. Once this tag
|
||
is set, then only the values can be changed using the same sysfs file / type
|
||
used to program it.
|
||
|
||
Thus::
|
||
|
||
% echo 0 > addr_idx ; select address comparator 0
|
||
% echo 0x1000 0x5000 0 > addr_range ; set address range on comparators 0, 1.
|
||
% echo 0x2000 > addr_start ; error as comparator 0 is a range comparator
|
||
% echo 2 > addr_idx ; select address comparator 2
|
||
% echo 0x2000 > addr_start ; this is OK as comparator 2 is unused.
|
||
% echo 0x3000 > addr_stop ; error as comparator 2 set as start address.
|
||
% echo 2 > addr_idx ; select address comparator 3
|
||
% echo 0x3000 > addr_stop ; this is OK
|
||
|
||
To remove programming on all the comparators (and all the other hardware) use
|
||
the reset parameter::
|
||
|
||
% echo 1 > reset
|
||
|
||
|
||
|
||
The ‘mode’ sysfs parameter.
|
||
---------------------------
|
||
|
||
This is a bitfield selection parameter that sets the overall trace mode for the
|
||
ETM. The table below describes the bits, using the defines from the driver
|
||
source file, along with a description of the feature these represent. Many
|
||
features are optional and therefore dependent on implementation in the
|
||
hardware.
|
||
|
||
Bit assignments shown below:-
|
||
|
||
----
|
||
|
||
**bit (0):**
|
||
ETM_MODE_EXCLUDE
|
||
|
||
**description:**
|
||
This is the default value for the include / exclude function when
|
||
setting address ranges. Set 1 for exclude range. When the mode
|
||
parameter is set this value is applied to the currently indexed
|
||
address range.
|
||
|
||
.. _coresight-branch-broadcast:
|
||
|
||
**bit (4):**
|
||
ETM_MODE_BB
|
||
|
||
**description:**
|
||
Set to enable branch broadcast if supported in hardware [IDR0]. The primary use for this feature
|
||
is when code is patched dynamically at run time and the full program flow may not be able to be
|
||
reconstructed using only conditional branches.
|
||
|
||
There is currently no support in Perf for supplying modified binaries to the decoder, so this
|
||
feature is only inteded to be used for debugging purposes or with a 3rd party tool.
|
||
|
||
Choosing this option will result in a significant increase in the amount of trace generated -
|
||
possible danger of overflows, or fewer instructions covered. Note, that this option also
|
||
overrides any setting of :ref:`ETM_MODE_RETURNSTACK <coresight-return-stack>`, so where a branch
|
||
broadcast range overlaps a return stack range, return stacks will not be available for that
|
||
range.
|
||
|
||
.. _coresight-cycle-accurate:
|
||
|
||
**bit (5):**
|
||
ETMv4_MODE_CYCACC
|
||
|
||
**description:**
|
||
Set to enable cycle accurate trace if supported [IDR0].
|
||
|
||
|
||
**bit (6):**
|
||
ETMv4_MODE_CTXID
|
||
|
||
**description:**
|
||
Set to enable context ID tracing if supported in hardware [IDR2].
|
||
|
||
|
||
**bit (7):**
|
||
ETM_MODE_VMID
|
||
|
||
**description:**
|
||
Set to enable virtual machine ID tracing if supported [IDR2].
|
||
|
||
.. _coresight-timestamp:
|
||
|
||
**bit (11):**
|
||
ETMv4_MODE_TIMESTAMP
|
||
|
||
**description:**
|
||
Set to enable timestamp generation if supported [IDR0].
|
||
|
||
.. _coresight-return-stack:
|
||
|
||
**bit (12):**
|
||
ETM_MODE_RETURNSTACK
|
||
**description:**
|
||
Set to enable trace return stack use if supported [IDR0].
|
||
|
||
|
||
**bit (13-14):**
|
||
ETM_MODE_QELEM(val)
|
||
|
||
**description:**
|
||
‘val’ determines level of Q element support enabled if
|
||
implemented by the ETM [IDR0]
|
||
|
||
|
||
**bit (19):**
|
||
ETM_MODE_ATB_TRIGGER
|
||
|
||
**description:**
|
||
Set to enable the ATBTRIGGER bit in the event control register
|
||
[EVENTCTLR1] if supported [IDR5].
|
||
|
||
|
||
**bit (20):**
|
||
ETM_MODE_LPOVERRIDE
|
||
|
||
**description:**
|
||
Set to enable the LPOVERRIDE bit in the event control register
|
||
[EVENTCTLR1], if supported [IDR5].
|
||
|
||
|
||
**bit (21):**
|
||
ETM_MODE_ISTALL_EN
|
||
|
||
**description:**
|
||
Set to enable the ISTALL bit in the stall control register
|
||
[STALLCTLR]
|
||
|
||
|
||
**bit (23):**
|
||
ETM_MODE_INSTPRIO
|
||
|
||
**description:**
|
||
Set to enable the INSTPRIORITY bit in the stall control register
|
||
[STALLCTLR] , if supported [IDR0].
|
||
|
||
|
||
**bit (24):**
|
||
ETM_MODE_NOOVERFLOW
|
||
|
||
**description:**
|
||
Set to enable the NOOVERFLOW bit in the stall control register
|
||
[STALLCTLR], if supported [IDR3].
|
||
|
||
|
||
**bit (25):**
|
||
ETM_MODE_TRACE_RESET
|
||
|
||
**description:**
|
||
Set to enable the TRCRESET bit in the viewinst control register
|
||
[VICTLR] , if supported [IDR3].
|
||
|
||
|
||
**bit (26):**
|
||
ETM_MODE_TRACE_ERR
|
||
|
||
**description:**
|
||
Set to enable the TRCCTRL bit in the viewinst control register
|
||
[VICTLR].
|
||
|
||
|
||
**bit (27):**
|
||
ETM_MODE_VIEWINST_STARTSTOP
|
||
|
||
**description:**
|
||
Set the initial state value of the ViewInst start / stop logic
|
||
in the viewinst control register [VICTLR]
|
||
|
||
|
||
**bit (30):**
|
||
ETM_MODE_EXCL_KERN
|
||
|
||
**description:**
|
||
Set default trace setup to exclude kernel mode trace (see note a)
|
||
|
||
|
||
**bit (31):**
|
||
ETM_MODE_EXCL_USER
|
||
|
||
**description:**
|
||
Set default trace setup to exclude user space trace (see note a)
|
||
|
||
----
|
||
|
||
*Note a)* On startup the ETM is programmed to trace the complete address space
|
||
using address range comparator 0. ‘mode’ bits 30 / 31 modify this setting to
|
||
set EL exclude bits for NS state in either user space (EL0) or kernel space
|
||
(EL1) in the address range comparator. (the default setting excludes all
|
||
secure EL, and NS EL2)
|
||
|
||
Once the reset parameter has been used, and/or custom programming has been
|
||
implemented - using these bits will result in the EL bits for address
|
||
comparator 0 being set in the same way.
|
||
|
||
*Note b)* Bits 2-3, 8-10, 15-16, 18, 22, control features that only work with
|
||
data trace. As A-profile data trace is architecturally prohibited in ETMv4,
|
||
these have been omitted here. Possible uses could be where a kernel has
|
||
support for control of R or M profile infrastructure as part of a heterogeneous
|
||
system.
|
||
|
||
Bits 17, 28-29 are unused.
|