On Thu, Jul 14, 2016 at 9:05 PM, Lee, Chun-Yi <joeyli.kernel@xxxxxxxxx> wrote: > This patch adds logic to treat virtual ramdisk SPA as pmem region, then > ramdisk's /dev/pmem* device can be mounted with iso9660. > > It's useful to work with the httpboot in EFI firmware to pull a remote > ISO file to the local memory region for booting and installation. > > Wiki page of UEFI HTTPBoot with OVMF: > https://en.opensuse.org/UEFI_HTTPBoot_with_OVMF > > The ramdisk function in EDK2/OVMF generates a ACPI0012 root device that > it contains empty _STA but without _DSM: > > DefinitionBlock ("ssdt2.aml", "SSDT", 2, "INTEL ", "RamDisk ", 0x00001000) > { > Scope (\_SB) > { > Device (NVDR) > { > Name (_HID, "ACPI0012") // _HID: Hardware ID > Name (_STR, Unicode ("NVDIMM Root Device")) // _STR: Description String > Method (_STA, 0, NotSerialized) // _STA: Status > { > Return (0x0F) > } > } > } > } > > In section 5.2.25.2 of ACPI 6.1 spec, it mentions that the "SPA Range > Structure Index" of virtual SPA shall be set to zero. That means virtual SPA > will not be associated by any NVDIMM region mapping. > > The VCD's SPA Range Structure in NFIT is similar to virtual disk region > as following: > > [028h 0040 2] Subtable Type : 0000 [System Physical Address Range] > [02Ah 0042 2] Length : 0038 > > [02Ch 0044 2] Range Index : 0000 > [02Eh 0046 2] Flags (decoded below) : 0000 > Add/Online Operation Only : 0 > Proximity Domain Valid : 0 > [030h 0048 4] Reserved : 00000000 > [034h 0052 4] Proximity Domain : 00000000 > [038h 0056 16] Address Range GUID : 77AB535A-45FC-624B-5560-F7B281D1F96E > [048h 0072 8] Address Range Base : 00000000B6ABD018 > [050h 0080 8] Address Range Length : 0000000005500000 > [058h 0088 8] Memory Map Attribute : 0000000000000000 > > The way to not associate a SPA range is to never reference it from a "flush hint", > "interleave", or "control region" table. > > After testing on OVMF, pmem driver can support the region that it doesn't > assoicate to any NVDIMM mapping. So, treat VCD like pmem is a idea to get > a pmem block device that it contains iso. > > v4: > Instoduce nfit_spa_is_virtual() to check virtual ramdisk SPA and create > pmem region. > > v3: > To simplify patch, removed useless VCD region in libnvdimm. > > v2: > Removed the code for setting VCD to a read-only region. > > Cc: Gary Lin <GLin@xxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> > Cc: Linda Knippers <linda.knippers@xxxxxxx> > Signed-off-by: Lee, Chun-Yi <jlee@xxxxxxxx> Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
