[...]
> > Some more details can be found here: > > > > https://linux.kernelci.org/test/case/id/6189968c3ec0a3c06e3358fe/ > > > > Here's the same revision on the same platform booting fine with a > > plain multi_v7_defconfig build: > > > > https://linux.kernelci.org/test/plan/id/61899d322c0e9fee7e3358ec/ > > > > Please let us know if you need any help debugging this issue or > > if you have a fix to try. > > The patch below is removing the dma mapping support in page pool > for 32 bit systems with 64 bit dma address, so it seems there > is indeed a a drvier using the the page pool with PP_FLAG_DMA_MAP > flags set in a 32 bit systems with 64 bit dma address. > > It seems we might need to revert the below patch or implement the > DMA-mapping tracking support in the driver as mentioned in the below > commit log. > > which ethernet driver do you use in your system?
Thanks for taking a look and sorry for the slow reply. Here's a booting test job with LPAE disabled:
https://linux.kernelci.org/test/plan/id/618dbb81c60c4d94503358f1/ https://storage.kernelci.org/mainline/master/v5.15-12452-g5833291ab6de/arm/multi_v7_defconfig/gcc-10/lab-collabora/baseline-nfs-rk3288-rock2-square.html#L812[ 8.314523] rk_gmac-dwmac ff290000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
So the driver is drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
Thanks for the report, this patch seems to cause problem for 32-bit system with LPAE enabled.
As LPAE seems like a common feature for 32 bits system, this patch might need to be reverted.
@Jesper, @Ilias, what do you think?
So enabling LPAE also enables CONFIG_ARCH_DMA_ADDR_T_64BIT on that board? Doing a quick grep only selects that for XEN. I am ok reverting that, but I think we need to understand how the dma address ended up being 64bit.
So looking a bit closer, indeed enabling LPAE always enables this. So we need to revert the patch. Yunsheng will you send that?
Sure.
Why don't we change that driver[1] to not use page_pool_get_dma_addr() ?
[1] drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
I took a closer look and it seems the driver have struct stmmac_rx_buffer in which is stored the dma_addr it gets from page_pool_get_dma_addr().
See func: stmmac_init_rx_buffers
static int stmmac_init_rx_buffers(struct stmmac_priv *priv, struct dma_desc *p, int i, gfp_t flags, u32 queue) {
if (!buf->page) { buf->page = page_pool_dev_alloc_pages(rx_q->page_pool); if (!buf->page) return -ENOMEM; buf->page_offset = stmmac_rx_offset(priv); } [...]
buf->addr = page_pool_get_dma_addr(buf->page) + buf->page_offset;
stmmac_set_desc_addr(priv, p, buf->addr); [...] }
I question if this driver really to use page_pool for storing the dma_addr as it just extract it and store it outside page_pool?
@Ilias it looks like you added part of the page_pool support in this driver, so I hope you can give a qualified guess on: How much work will it be to let driver do the DMA-map itself? (and not depend on the DMA-map feature provided by page_pool)
It shouldn't be that hard. However when we removed that we were hoping we had no active consumers. So we'll have to fix this and check for other 32-bit boards with LPAE and page_pool handling the DMA mappings. But the point now is that this is far from a 'hardware configuration' of 32-bit CPU + 64-bit DMA. Every armv7 and x86 board can get that. So I was thinking it's better to revert this and live with the 'weird' handling in the code.
Cheers /Ilias