On Tue, Aug 23, 2022 at 11:25 AM Dongli Zhang <dongli.zhang@xxxxxxxxxx> wrote: > > Adding Robin, Yu and swiotlb list. Thanks. > There is an on-going discussion whether to revert this patch, because it breaks > a corner case in MIPS I wouldn't call it a corner case. Cavium Octeon is the major platform we use to test Debian MIPS ports [1], and 4 out of 5 best-selling Wi-Fi routers are MIPS-based [2]. [1] https://wiki.debian.org/MIPSPort [2] https://www.amazon.com/bestsellers/pc/300189 > when many kernel CONFIGs are not enabled (related to PCI > and device). As a result, MIPS pre-allocates only PAGE_SIZE buffer as swiotlb. > > https://lore.kernel.org/all/20220820012031.1285979-1-yuzhao@xxxxxxxxxx/ > > However, the core idea of the patch is to panic on purpose if the swiotlb is > configured with <1MB memory, in order to sync with the remap failure handler in > swiotlb_init_remap(). > > Therefore, I am waiting for suggestion from Christoph whether (1) to revert this > patch, or (2) enforce the restriction to disallow <1MB allocation. There are other archs (arm, ppc, riscv, s390, etc.) that call swiotlb_init(). Have you verified them all?
