| Message ID | 1403499940-11258-1-git-send-email-msalter@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 23 Jun 2014, Mark Salter wrote: > Commit 2d5a5612bc (arm64: Limit the CMA buffer to 32-bit if ZONE_DMA) > forces the CMA buffer to be 32-bit addressable if CONFIG_ZONE_DMA is > defined. This breaks CMA on platforms with no 32-bit addressable DRAM. > This patch checks to make sure there is 32-bit addressable DRAM before > setting the 32-bit limit. If there is none, no limit is placed on the > CMA buffer. This allows a single kernel (with CONFIG_ZONE_DMA defined) > to support platforms requiring the 32-bit limit and platforms with no > 32-bit limit. > > Signed-off-by: Mark Salter <msalter@redhat.com> > --- > arch/arm64/mm/init.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index c5415e2..2925576 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -149,8 +149,17 @@ void __init arm64_memblock_init(void) > early_init_fdt_scan_reserved_mem(); > > /* 4GB maximum for 32-bit only capable devices */ > - if (IS_ENABLED(CONFIG_ZONE_DMA)) > + if (IS_ENABLED(CONFIG_ZONE_DMA)) { > dma_phys_limit = dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1; > + /* > + * If platform doesn't have DRAM within the dma_phys_limit, > + * remove the limit altogether. This allows one kernel (with > + * CONFIG_ZONE_DMA defined) to support platforms with 32-bit > + * only devices and platforms with no 32-bit DRAM. > + */ > + if (dma_phys_limit <= memblock_start_of_DRAM()) > + dma_phys_limit = 0; > + } > dma_contiguous_reserve(dma_phys_limit); > > memblock_allow_resize(); It is a shame that we have very similar logic, all dependent on memblock_start_of_DRAM(), in both zone_sizes_init() and arm64_memblock_init() and the latter having to be called before the former. I assume there's no way to make this cleaner in the bootstrap code so the dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1 limit can be handled properly in a single location? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Wed, Jun 25, 2014 at 01:26:02AM +0100, David Rientjes wrote: > On Mon, 23 Jun 2014, Mark Salter wrote: > > > Commit 2d5a5612bc (arm64: Limit the CMA buffer to 32-bit if ZONE_DMA) > > forces the CMA buffer to be 32-bit addressable if CONFIG_ZONE_DMA is > > defined. This breaks CMA on platforms with no 32-bit addressable DRAM. > > This patch checks to make sure there is 32-bit addressable DRAM before > > setting the 32-bit limit. If there is none, no limit is placed on the > > CMA buffer. This allows a single kernel (with CONFIG_ZONE_DMA defined) > > to support platforms requiring the 32-bit limit and platforms with no > > 32-bit limit. > > > > Signed-off-by: Mark Salter <msalter@redhat.com> > > --- > > arch/arm64/mm/init.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > index c5415e2..2925576 100644 > > --- a/arch/arm64/mm/init.c > > +++ b/arch/arm64/mm/init.c > > @@ -149,8 +149,17 @@ void __init arm64_memblock_init(void) > > early_init_fdt_scan_reserved_mem(); > > > > /* 4GB maximum for 32-bit only capable devices */ > > - if (IS_ENABLED(CONFIG_ZONE_DMA)) > > + if (IS_ENABLED(CONFIG_ZONE_DMA)) { > > dma_phys_limit = dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1; > > + /* > > + * If platform doesn't have DRAM within the dma_phys_limit, > > + * remove the limit altogether. This allows one kernel (with > > + * CONFIG_ZONE_DMA defined) to support platforms with 32-bit > > + * only devices and platforms with no 32-bit DRAM. > > + */ > > + if (dma_phys_limit <= memblock_start_of_DRAM()) > > + dma_phys_limit = 0; > > + } > > dma_contiguous_reserve(dma_phys_limit); > > > > memblock_allow_resize(); > > It is a shame that we have very similar logic, all dependent on > memblock_start_of_DRAM(), in both zone_sizes_init() and > arm64_memblock_init() and the latter having to be called before the > former. I assume there's no way to make this cleaner in the bootstrap > code so the dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1 limit can be handled > properly in a single location? Probably and I suggested something along the lines of only calculating it once in reply to the "[PATCH] arm64: make CONFIG_ZONE_DMA user settable" message. I'll follow up on the other thread (Mark considers there's a penalty issue with all memory in the DMA zone).
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index c5415e2..2925576 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -149,8 +149,17 @@ void __init arm64_memblock_init(void) early_init_fdt_scan_reserved_mem(); /* 4GB maximum for 32-bit only capable devices */ - if (IS_ENABLED(CONFIG_ZONE_DMA)) + if (IS_ENABLED(CONFIG_ZONE_DMA)) { dma_phys_limit = dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1; + /* + * If platform doesn't have DRAM within the dma_phys_limit, + * remove the limit altogether. This allows one kernel (with + * CONFIG_ZONE_DMA defined) to support platforms with 32-bit + * only devices and platforms with no 32-bit DRAM. + */ + if (dma_phys_limit <= memblock_start_of_DRAM()) + dma_phys_limit = 0; + } dma_contiguous_reserve(dma_phys_limit); memblock_allow_resize();
Commit 2d5a5612bc (arm64: Limit the CMA buffer to 32-bit if ZONE_DMA) forces the CMA buffer to be 32-bit addressable if CONFIG_ZONE_DMA is defined. This breaks CMA on platforms with no 32-bit addressable DRAM. This patch checks to make sure there is 32-bit addressable DRAM before setting the 32-bit limit. If there is none, no limit is placed on the CMA buffer. This allows a single kernel (with CONFIG_ZONE_DMA defined) to support platforms requiring the 32-bit limit and platforms with no 32-bit limit. Signed-off-by: Mark Salter <msalter@redhat.com> --- arch/arm64/mm/init.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)