This patch adds support for the XTheadSync ISA extension.
The patch uses the T-Head specific decoder and translation.
The implementation introduces a helper to execute synchronization tasks:
helper_tlb_flush_all() performs a synchronized TLB flush on all CPUs.
Co-developed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Message-Id: <20230131202013.2541053-3-christoph.muellner@vrull.eu>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Since priv spec v1.12, MRET and SRET now clear mstatus.MPRV when
leaving M-mode.
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221207090037.281452-2-bmeng@tinylab.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
There are 2 paths in helper_sret() and the same mstatus update codes
are replicated. Extract the common parts to simplify it a little bit.
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221207090037.281452-1-bmeng@tinylab.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
The priv spec v1.12 says:
If no PMP entry matches an M-mode access, the access succeeds. If
no PMP entry matches an S-mode or U-mode access, but at least one
PMP entry is implemented, the access fails. Failed accesses generate
an instruction, load, or store access-fault exception.
At present the exception cause is set to 'illegal instruction' but
should have been 'instruction access fault'.
Fixes: d102f19a20 ("target/riscv/pmp: Raise exception if no PMP entry is configured")
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221205065303.204095-1-bmeng@tinylab.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
- add SEED CSR which must be accessed with a read-write instruction:
A read-only instruction such as CSRRS/CSRRC with rs1=x0 or CSRRSI/CSRRCI
with uimm=0 will raise an illegal instruction exception.
- add USEED, SSEED fields for MSECCFG CSR
Co-authored-by: Ruibo Lu <luruibo2000@163.com>
Co-authored-by: Zewen Ye <lustrew@foxmail.com>
Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220423023510.30794-13-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
G_NORETURN was introduced in glib 2.68, fallback to G_GNUC_NORETURN in
glib-compat.
Note that this attribute must be placed before the function declaration
(bringing a bit of consistency in qemu codebase usage).
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20220420132624.2439741-20-marcandre.lureau@redhat.com>
Write mask is representing the bits we care about.
Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220120122050.41546-11-zhiwei_liu@c-sky.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
As pc will be written by the xepc in exception return, just ignore
pc in translation.
Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220120122050.41546-3-zhiwei_liu@c-sky.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Given the side effects they have, the csr instructions are realized as
helpers. We extend this existing infrastructure for 128-bit sized csr.
We return 128-bit values using the same approach as for div/rem.
Theses helpers all call a unique function that is currently a fallback
on the 64-bit version.
The trans_csrxx functions supporting 128-bit are yet to be implemented.
Signed-off-by: Frédéric Pétrot <frederic.petrot@univ-grenoble-alpes.fr>
Co-authored-by: Fabien Portas <fabien.portas@grenoble-inp.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220106210108.138226-17-frederic.petrot@univ-grenoble-alpes.fr
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
As per the privilege specification, any access from S/U mode should fail
if no pmp region is configured and pmp is present, othwerwise access
should succeed.
Fixes: d102f19a20 (target/riscv/pmp: Raise exception if no PMP entry is configured)
Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20211214092659.15709-1-nikita.shubin@maquefel.me
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Introduce csrr and csrw helpers, for read-only and write-only insns.
Note that we do not properly implement this in riscv_csrrw, in that
we cannot distinguish true read-only (rs1 == 0) from any other zero
write_mask another source register -- this should still raise an
exception for read-only registers.
Only issue gen_io_start for CF_USE_ICOUNT.
Use ctx->zero for csrrc.
Use get_gpr and dest_gpr.
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210823195529.560295-19-richard.henderson@linaro.org
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
The wfi exception trigger behavior should take into account user mode,
hstatus.vtw, and the fact the an wfi might raise different types of
exceptions depending on various factors:
If supervisor mode is not present:
- an illegal instruction exception should be generated if user mode
executes and wfi instruction and mstatus.tw = 1.
If supervisor mode is present:
- when a wfi instruction is executed, an illegal exception should be triggered
if either the current mode is user or the mode is supervisor and mstatus.tw is
set.
Plus, if the hypervisor extensions are enabled:
- a virtual instruction exception should be raised when a wfi is executed from
virtual-user or virtual-supervisor and hstatus.vtw is set.
Signed-off-by: Jose Martins <josemartins90@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210420213656.85148-1-josemartins90@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Many files include qemu/log.h without needing it. Remove the superfluous
include statements.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20210328054833.2351597-1-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
As per the privilege specification, any access from S/U mode should fail
if no pmp region is configured.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20201223192553.332508-1-atish.patra@wdc.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Split the hypervisor execute load functions into two seperate functions.
This avoids us having to pass the memop to the C helper functions.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 5b1550f0faa3c435cc77f3c1ae811dea98ab9e36.1604464950.git.alistair.francis@wdc.com
Remove the special Virtulisation load and store functions and just use
the standard tcg tcg_gen_qemu_ld_tl() and tcg_gen_qemu_st_tl() functions
instead.
As part of this change we ensure we still run an access check to make
sure we can perform the operations.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 189ac3e53ef2854824d18aad7074c6649f17de2c.1604464950.git.alistair.francis@wdc.com
The HS_TWO_STAGE flag is no longer required as the MMU index contains
the information if we are performing a two stage access.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: f514b128b1ff0fb41c85f914cee18f905007a922.1604464950.git.alistair.francis@wdc.com
When performing the hypervisor load/store operations set the MMU mode to
indicate that we are virtualised.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: e411c61a1452cad16853f13cac2fb86dc91ebee8.1604464950.git.alistair.francis@wdc.com
mstatus/mstatush and vsstatus/vsstatush are two halved for RISCV32.
This patch expands mstatus and vsstatus to uint64_t instead of
target_ulong so that it can be saved as one unit and reduce some
ifdefs in the code.
Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Yipeng Yin <yinyipeng1@huawei.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20201026115530.304-2-jiangyifei@huawei.com
The HLVX.WU instruction is supposed to read a machine word,
but prior to this change it read a byte instead.
Fixes: 8c5362acb5 ("target/riscv: Allow generating hlv/hlvx/hsv instructions")
Signed-off-by: Georg Kotheimer <georg.kotheimer@kernkonzept.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20201013172223.443645-1-georg.kotheimer@kernkonzept.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Currently we log interrupts and exceptions using the trace backend in
riscv_cpu_do_interrupt(). We also log exceptions using the interrupt log
mask (-d int) in riscv_raise_exception().
This patch converts riscv_cpu_do_interrupt() to log both interrupts and
exceptions with the interrupt log mask, so that both are printed when a
user runs QEMU with -d int.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 29a8c766c7c4748d0f2711c3a0abb81208138c5e.1601652179.git.alistair.francis@wdc.com
When performing a CSR access let's return a negative exception value on
an error instead of -1. This will allow us to specify the exception in
future patches.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: a487dad60c9b8fe7a2b992c5e0dcc2504a9000a7.1597259519.git.alistair.francis@wdc.com
Message-Id: <a487dad60c9b8fe7a2b992c5e0dcc2504a9000a7.1597259519.git.alistair.francis@wdc.com>
Call the helper_hyp_tlb_flush() function on hfence instructions which
will generate an illegal insruction execption if we don't have
permission to flush the Hypervisor level TLBs.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
The RISC-V ISA spec version 1.09.1 has been deprecated in QEMU since
4.1. It's not commonly used so let's remove support for it.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
As reported in: https://bugs.launchpad.net/qemu/+bug/1851939 we weren't
correctly handling illegal instructions based on the value of MSTATUS_TSR
and the current privledge level.
This patch fixes the issue raised in the bug by raising an illegal
instruction if TSR is set and we are in S-Mode.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Jonathan Behrens <jonathan@fintelia.io
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Add a helper macro MSTATUS_MPV_ISSET() which will determine if the
MSTATUS_MPV bit is set for both 32-bit and 64-bit RISC-V.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
When executing an xRET instruction, supposing xPP holds the
value y, xIE is set to xPIE; the privilege mode is changed to y;
xPIE is set to 1. But QEMU sets xPIE to 0 incorrectly.
Signed-off-by: Yiting Wang <yiting.wang@windriver.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Cleanup in the boilerplate that each target must define.
Replace riscv_env_get_cpu with env_archcpu. The combination
CPU(riscv_env_get_cpu) should have used ENV_GET_CPU to begin;
use env_cpu now.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The 'sfence.vma' instruction is privileged, and should only ever be allowed
when executing in supervisor mode or higher.
Signed-off-by: Jonathan Behrens <fintelia@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
* Add riscv prefix to raise_exception function
* Add riscv prefix to CSR read/write functions
* Add riscv prefix to signal handler function
* Add riscv prefix to get fflags function
* Remove redundant declaration of riscv_cpu_init
and rename cpu_riscv_init to riscv_cpu_init
* rename riscv_set_mode to riscv_cpu_set_mode
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This adds the necessary minimum to support S-mode
virtualization for priv ISA >= v1.10
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Co-authored-by: Matthew Suozzo <msuozzo@google.com>
Co-authored-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Previous CSR code uses csr_read_helper and csr_write_helper
to update CSR registers however this interface prevents
atomic read/modify/write CSR operations; in addition
there is no trap-free method to access to CSRs due
to the monolithic CSR functions call longjmp.
The current iCSR interface is not safe to be called by
target/riscv/gdbstub.c as privilege checks or missing CSRs
may call longjmp to generate exceptions. It needs to
indicate existence so traps can be generated in the
CSR instruction helpers.
This commit moves CSR access from the monolithic switch
statements in target/riscv/op_helper.c into modular
read/write functions in target/riscv/csr.c using a new
function pointer table for dispatch (which can later
be used to allow CPUs to hook up model specific CSRs).
A read/modify/write interface is added to support atomic
CSR operations and a non-trapping interface is added
to allow exception-free access to CSRs by the debugger.
The CSR functions and CSR dispatch table are ordered
to match The RISC-V Instruction Set Manual, Volume II:
Privileged Architecture Version 1.10, 2.2 CSR Listing.
An API is added to allow derived cpu instances to modify
or implement new CSR operations.
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
* Add user-mode CSR defininitions.
* Reorder CSR definitions to match the specification.
* Change H mode interrupt comment to 'reserved'.
* Remove unused X_COP interrupt.
* Add user-mode interrupts.
* Remove erroneous until comments on machine mode interrupts.
* Move together paging mode and page table bit definitions.
* Move together interrupt and exception cause definitions.
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This patch makes op_helper.c contain only instruction
operation helpers used by translate.c and moves any
unrelated cpu helpers into cpu_helper.c. No logic is
changed by this patch.
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Change the API of riscv_set_local_interrupt to take a
write mask and value to allow setting and clearing of
multiple local interrupts atomically in a single call.
Rename the new function to riscv_cpu_update_mip.
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180606152128.449-11-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
These fields are marked WARL (Write Any Values, Reads
Legal Values) in the RISC-V Privileged Architecture
Specification so instead of raising exceptions,
illegal writes are silently dropped.
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Vectored traps for asynchrounous interrupts are optional.
The mtvec/stvec mode field is WARL and hence does not trap
if an illegal value is written. Illegal values are ignored.
Later we can add RISCV_FEATURE_VECTORED_TRAPS however
until then the correct behavior for WARL (Write Any, Read
Legal) fields is to drop writes to unsupported bits.
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Previously the mycycle/minstret CSRs and rdcycle/rdinstret
psuedo instructions would return the time as a proxy for an
increasing instruction counter in the absence of having a
precise instruction count. If QEMU is invoked with -icount,
the mcycle/minstret CSRs and rdcycle/rdinstret psuedo
instructions will return the instruction count.
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Privileged ISA v1.9.1 defines mscounteren and mucounteren:
* mscounteren contains a mask of counters available to S-mode
* mucounteren contains a mask of counters available to U-mode
Privileged ISA v1.10 defines mcounteren and scounteren:
* mcounteren contains a mask of counters available to S-mode
* scounteren contains a mask of counters available to U-mode
mcounteren and scounteren CSR registers were implemented
however they were not honoured for counter accesses when
the privilege ISA was >= v1.10. This fix solves the issue
by coalescing the counter enable registers. In addition
the code now generates illegal instruction exceptions
for accesses to the counter enabled registers depending
on the privileged ISA version.
- Coalesce mscounteren and mcounteren into one variable
- Coalesce mucounteren and scounteren into one variable
- Makes mcounteren and scounteren CSR accesses generate
illegal instructions when the privileged ISA <= v1.9.1
- Makes mscounteren and mucounteren CSR accesses generate
illegal instructions when the privileged ISA >= v1.10
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
The mstatus.MXR alias in sstatus should only be writable
by S-mode if the privileged ISA version >= v1.10. Also MXR
was masked in sstatus CSR read but not sstatus CSR writes.
Now we correctly mask sstatus.mxr in both read and write.
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
satp is WARL so it should not trap on illegal writes, rather
it can be hardwired to zero and silently ignore illegal writes.
It seems the RISC-V WARL behaviour is preferred to having to
trap overhead versus simply reading back the value and checking
if the write took (saves hundreds of cycles and more complex
trap handling code).
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
This change is a workaround for a bug where mstatus.FS
is not correctly reporting dirty after operations that
modify floating point registers. This a critical bug
or RISC-V in QEMU as it results in floating point
register file corruption when running SMP Linux due to
task migration and possibly uniprocessor Linux if
more than one process is using the FPU.
This workaround will return dirty if mstatus.FS is
switched from off to initial or clean. According to
the specification it is legal for an implementation
to return only off, or dirty.
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
