I am fine with this change as is.

On Tue, Jan 28, 2025 at 7:51 AM Randy MacLeod
<[email protected]> wrote:
>
> 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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