Add Raj, Khem, Kexin and Zhe who know more about RISC-V than I do.
Kexin and Zhe are on holiday for a week or more.
CC a few people who have contributed to riscv* conf.
I am not all that familiar with either qemu internals or riscv
specifications so any input is appreciated.
I have some comments and questions below.
On 2025-01-28 5:16 a.m., [email protected] wrote:
From: Yash Shinde<[email protected]>
Currently, GCC Asan supports only Sv39 on RISC-V due to custom allocator
configurations optimized for large allocations.
These configurations are incompatible with larger address spaces like Sv48/Sv57.
This fix enables RISC-V's configuration for Sv39 by default when running
`runqemu nographic`,
eliminating the need for manual configuration via command line flags
(`qemuparams="-cpu rv64, sv39=true"`).
Fixes [YOCTO #15691]
https://bugzilla.yoctoproject.org/show_bug.cgi?id=15691
Reference:https://git.openembedded.org/openembedded-core/commit/?id=4b4450ff695ef73bf7a2437e142d2e0730d6a547
Signed-off-by: Yash Shinde<[email protected]>
---
meta/conf/machine/include/riscv/qemuriscv.inc | 1 +
1 file changed, 1 insertion(+)
diff --git a/meta/conf/machine/include/riscv/qemuriscv.inc
b/meta/conf/machine/include/riscv/qemuriscv.inc
index d01d988eee..6170ce65f2 100644
--- a/meta/conf/machine/include/riscv/qemuriscv.inc
+++ b/meta/conf/machine/include/riscv/qemuriscv.inc
@@ -27,6 +27,7 @@ UBOOT_ENTRYPOINT:riscv64 = "0x80200000"
# qemuboot options
QB_SMP ?= "-smp 4"
QB_KERNEL_CMDLINE_APPEND = "earlycon=sbi"
+QB_CPU = "-cpu rv64, sv39=true"
Thanks Yash.
To save everyone from doing the math, sv39 gives the system 512 GB
virtual address space.
Should we use the ?= operator here so that users can easily override
this specification
just as is done for QB_SMP two lines above?
Please summarize what testing you did.
Did you test with TCLIBC=musl ?
Since you are changing qemuriscv.inc you and the YP AB should test
qemuriscv32 and qemuriscv64.
qemuriscv32 should, if I'm understanding how this works, be unaffected
since it has to use sv32 mode.
Did you find out why sv39 isn't the default for qemu?
If not, please check the git history and it there isn't an answer there,
ask one of the qemu developers
who work on risc-v. It would be nice to have a sentence about that in
the commit log.
Did you consider a different RISC-V cpu sub-arch such as rva22s64 ?
https://github.com/qemu/qemu/commit/3ba8462c4ca55720239fdc6fa30b9870d22a8814
I'm only asking because it seems like it might be a good fit for us and
I noticed it when
searching the qemu commit logs looking for sv39.
../Randy
QB_MACHINE = "-machine virt"
QB_DEFAULT_BIOS = "fw_jump.elf"
QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no"
--
# Randy MacLeod
# Wind River Linux
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