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Diffstat (limited to 'results/classifier/gemma3:27b/runtime/2304')
| -rw-r--r-- | results/classifier/gemma3:27b/runtime/2304 | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/results/classifier/gemma3:27b/runtime/2304 b/results/classifier/gemma3:27b/runtime/2304 new file mode 100644 index 00000000..98b4e73d --- /dev/null +++ b/results/classifier/gemma3:27b/runtime/2304 @@ -0,0 +1,41 @@ + + + +Disabling SVE via `-cpu max,sve=off` leaves SVE2 advertised by `getauxval` +Description of problem: +The documentation on https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html suggests that it should be possible to disable SVE support by passing `-cpu max,sve=off` on the command line, however this appears to only disable the SVE support advertised in the return value from `getauxval(AT_HWCAP)`. In particular it leaves SVE2 reported as enabled. This leaves the feature set advertised by `getauxval` in an inconsistent state since SVE is mandatory if SVE2 is available. + +This may also affect other feature dependencies for example FEAT_SVE_BITPerm also requiring SVE2 to be available, I've not checked exhaustively. + +For example, given the following code: + + #include <sys/auxv.h> + #include <stdio.h> + + int main() { + unsigned long hwcap = getauxval(AT_HWCAP); + unsigned long hwcap2 = getauxval(AT_HWCAP2); + + if (hwcap & HWCAP_SVE) { + printf("have sve!\n"); + } else { + printf("don't have sve!\n"); + } + if (hwcap2 & HWCAP2_SVE2) { + printf("have sve2!\n"); + } else { + printf("don't have sve2!\n"); + } + } + +We can observe the following: + + $ aarch64-linux-gnu-gcc test.c -static + $ ../qemu-aarch64 -cpu max ./a.out + have sve! + have sve2! + $ ../qemu-aarch64 -cpu max,sve=off ./a.out + don't have sve! + have sve2! + +I don't believe that there is a `-cpu ...,sve2=off` option, so I would expect that disabling SVE also prevents SVE2 from being advertised as available. |