[RFC PATCH v1 0/2] drivers/block: add RamShared hardware-accelerated VRAM block driver

[RFC PATCH v1 0/2] drivers/block: add RamShared hardware-accelerated VRAM block driver

[emersonbusson]

This patch series introduces the RamShared hardware-accelerated block driver
(drivers/block/ramshared).

RamShared maps discrete GPU video memory (VRAM) apertures over direct PCIe
DMA to provide an ultra-low latency, non-rotational block device with a
synchronous .rw_page swapout path.

Key Design Highlights:
1. blk-mq multi-queue parallel request processing with atomic gendisk allocation.
2. Synchronous .rw_page fast-path in block_device_operations for zero-allocation
   swapout under direct memory reclaim pressure.
3. PCIe AER error handling with pci_error_handlers to contain link resets.
4. Comprehensive multi-kernel compatibility across 5.15 LTS through 6.18+.

Testing & Quality Gates:
- checkpatch.pl --strict: 0 errors, 0 warnings, 0 checks.
- sparse semantic address-space analysis: PASS (__iomem annotations verified).
- Multi-tier saturation benchmark: 9,160 MB swap holding 40 continuous cycles
  over 30 seconds with 0.00 ms access latency under WSL2/Hyper-V.

Signed-off-by: emersonbusson <emersonbusson@gmail.com>