News › linux
By The Linux Camp News, October 17, 2026
The kernel will stop trusting Immediate Readiness on Samsung 990 PRO and 990 EVO Plus SSDs, restoring a post-reset wait needed for reliable VFIO passthrough.
Linux merged a PCI workaround for Samsung 990 PRO and 990 EVO Plus NVMe SSDs on October 17, 2026 UTC, addressing reset failures affecting VFIO passthrough. Torvalds' merge timestamp is October 16 in its local timezone. As of the October 17 source retrieval, this was merged code, not a confirmed stable release; Phoronix expected Linux 7.3 on October 18. 3 1 2
Immediate Readiness advertises that a device can accept configuration requests immediately after reset. Linux trusts that indication and skips waiting after a Function Level Reset, or FLR. But the fix's commit message reports that the 990 PRO can return all-ones data, written as ~0, for up to 7 milliseconds instead of being ready. 1 5 2
The merge description places the regression in Linux 7.2. Removing retries during restoration of Base Address Registers, or BARs, exposed the readiness problem: configuration restoration happens too early and is lost, breaking VFIO drive passthrough. That makes reset handling the relevant troubleshooting path; the documented failure is not a general SSD throughput finding. 3 2
The new quirk, a device-specific kernel workaround, clears Linux's imm_ready flag for Samsung device IDs a80c and a80d. This makes pcie_flr() wait rather than trust the advertised capability. It changes kernel behavior, not SSD firmware; an already-clear flag is left alone. 4 2
Firmware coverage is incomplete. The commit says 990 PRO firmware 8B2QJXD7 responds immediately, unlike older firmware such as 1B2QJXD7. Helgaas describes the EVO Plus with 2B2QKXG7 as apparently having the same problem. Because firmware versions are unavailable at this point in the PCI code, the workaround selects devices by ID rather than firmware. 2 4
For this regression, check whether the running kernel contains commit 0f8b5d90d179b9639be1dbeff59d6d971e6b0527 or an equivalent distribution backport, rather than checking only installed packages or the base version. The supplied sources establish the upstream fix, but not distribution availability as of October 17. 2 4