vm_stress — TLB pressure mixed with an identity-mapped physical buffer - #405
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…ped buffer Every task strides across pages with an odd stride so consecutive touches spread across TLB sets, while also reading a bias through a pinned-slab identity mapping — paged and identity translations contend in the same run, which no existing vm_test mode does. The physical buffer is allocated, released, and allocated again first so the identity map is re-installed over a recycled slab range (the re-map must be idempotent and quiet). Wired into the default regression list and the vm catalog (simx + rtlsim, both XLENs, VORTEX_RANDOMIZE_VA=1). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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This adds a vm_stress regression test covering a translation pattern no existing vm mode exercises: paged and identity-mapped accesses contending in the same kernel.
Every task strides across pages with an odd stride so consecutive touches spread across TLB sets, while also reading a bias value through a VX_MEM_PHYS pinned-slab identity mapping — so L1/L2 TLB pressure and identity translations hit the MMU together. The host side allocates, releases, and re-allocates the physical buffer before launch, so the identity map is re-installed over a recycled slab range: the re-map must be idempotent and quiet, which regressed once during development and is now pinned by this test.
Wired into the default regression list and the vm test catalog (simx + rtlsim, XLEN 32/64, VORTEX_RANDOMIZE_VA=1).
Validated on this base: full vm catalog green on simx and rtlsim, both XLENs. Independent of the other VM PRs.