> On Fri, Feb 13, 2026 at 07:47:08AM +0000, Yasunori Goto (Fujitsu) wrote: > > Hello, Alison-san, > > > > I would like to clarify your answer a bit more. > > > > > On Thu, Feb 12, 2026 at 03:44:15PM +0100, Tomasz Wolski wrote: > > > > > > > > > >FYI - I am able to confirm the dax regions are back for > > > > >no-soft-reserved case, and my basic hotplug flow works with v6. > > > > > > > > > >-- Alison > > > > > > > > Hello Alison, > > > > > > > > I wanted to ask about this scenario. > > > > Is my understanding correct that this fix is needed for cases > > > > without Soft > > > Reserve and: > > > > 1) CXL memory is installed in the server (no hotplug) and OS is > > > > started > > > > 2) CXL memory is hot-plugged after the OS starts > > > > 3) Tests with cxl-test driver > > > or QEMU > > > > Though I can understand that cases 2) and 3) include QEMU, I'm not sure > why Linux drivers must handle case 1). > > In such a case, I feel that the platform vendor should modify the firmware > > to > define EFI_MEMORY_SP. > > > > In the past, I actually encountered another issue between our platform > firmware and a Linux driver: > > > https://lore.kernel.org/linux-cxl/OS9PR01MB12421AEA8B27BF942CD0F18B1 > 90 > > [email protected]/ > > In that case, I asked our firmware team to modify the firmware, and the > > issue > was resolved. > > > > Therefore, I would like to confirm why case 1) must be handled. > > Have any actual machines already been released with such firmware? > > Otherwise, is this just to prepare for a platform whose firmware cannot be > fixed on the firmware side? > > Maybe I'm misunderstanding Tomasz's Case 1), because this is not a > work-around for a firmware issue. > > The CXL driver always tries to create DAX regions out of RAM regions. > That happens if the CXL region is BIOS defined 'auto' region or a region > requested via userspace. That is irregardless of Soft Reserved existence. > Soft-Reserved is not a requirement for CXL or DAX region creation.
I misunderstood it I'll re-check the specifications. Sorry for the noise. > > That piece broke in an earlier rev of this patchset [1] where the calls to > devm_cxl_add_dax_region(cxlr) started returning EPROBE_DEFER. > > I intended to point out to Smita, that behavior is restored in v6. Thank you very much. ----- Yasunori Goto
