From 69c4a0ef86a22b384d887d5dae76cc13af43b5eb Mon Sep 17 00:00:00 2001 From: Mark Johnston Date: Thu, 25 Jan 2024 16:33:46 -0500 Subject: [PATCH] arm64: Add a VM_FREELIST_DMA32 freelist When booting a KMSAN kernel on an Ampere Altra, I've seen some boot time hangs when the XHCI controller driver attempts to allocate memory for 32-bit DMA. The system boots fine with a GENERIC kernel; I believe that the additional memory requirements of KMSAN push it over the edge. The system has a bit less than 2GB of RAM below the 4GB boundary. Allocate a new freelist to segregate memory below 4GB, as we do on amd64, so that such memory allocation failures are less likely to occur. Reviewed by: alc MFC after: 1 month Sponsored by: Klara, Inc. Sponsored by: Juniper Networks, Inc. Differential Revision: https://reviews.freebsd.org/D43503 (cherry picked from commit 48d5dab7bace6bae938672784ca3aa8733d72eb9) --- sys/arm64/include/vmparam.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/sys/arm64/include/vmparam.h b/sys/arm64/include/vmparam.h index 29fbf622198..0176045f0ca 100644 --- a/sys/arm64/include/vmparam.h +++ b/sys/arm64/include/vmparam.h @@ -85,11 +85,13 @@ #define VM_FREEPOOL_DIRECT 1 /* - * Create one free page lists: VM_FREELIST_DEFAULT is for all physical - * pages. + * Create two free page lists: VM_FREELIST_DMA32 is for physical pages that have + * physical addresses below 4G, and VM_FREELIST_DEFAULT is for all other + * physical pages. */ -#define VM_NFREELIST 1 +#define VM_NFREELIST 2 #define VM_FREELIST_DEFAULT 0 +#define VM_FREELIST_DMA32 1 /* * When PAGE_SIZE is 4KB, an allocation size of 16MB is supported in order