plat/xen, drivers/pl011: Fix PL011 UART mapping on Xen/arm64 - #1885
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kang-yoongu wants to merge 2 commits into
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plat/xen, drivers/pl011: Fix PL011 UART mapping on Xen/arm64#1885kang-yoongu wants to merge 2 commits into
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Xen inserts "arm,sbsa-uart" as the compatible string for the vpl011 node in the guest DTB. Add it to the fdt_compatible list so the PL011 driver can match the device on Xen dom0less guests. Signed-off-by: Peter Kang <peter.kang@boeing.com> Signed-off-by: Anderson Choi <anderson.choi@boeing.com>
On Xen, IPA cannot be used directly as a VA. Add FIX_PL011 fixmap region in xen-arm/mm.h and use set_pgt_entry() in the PL011 driver to map the UART MMIO address through the fixmap page table when running on Xen. This avoids direct use of physical address as VA. - Add FIX_PL011_TOP/START to fixmap layout in xen-arm/mm.h - Add FIXMAP_ENTRIES macro (PAGE_SIZE / sizeof(lpae_t)) - Move extern fixmap_pgtable declaration into mm.h - Use set_pgt_entry() API (includes dsb ishst + isb) instead of direct assignment, consistent with other fixmap users in setup64.c Signed-off-by: Peter Kang <peter.kang@boeing.com> Signed-off-by: Anderson Choi <anderson.choi@boeing.com>
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On Xen/ARM64 dom0less boot, the unikernel crashes immediately with repeated data abort traps before any console output appears.
Root causes:
In dom0less environment, HYPERVISOR_start_info is not initialized (remains 0x0). The xenconsole driver attempts to write pointer derived from start_info, which is NULL, triggering a data abort trap on every uk_pr_* / printk call.
The PL011 UART driver uses the physical/IPA address from the FDT reg property directly as a virtual address (dev->base = reg_base). Under Xen, guest IPA is not identity-mapped to VA, so UART register accesses hit an incorrect virtual address.
Description of Changes
This series fixes PL011 UART initialization on Xen/arm64 dom0less guests.
On Xen, IPA cannot be used directly as a VA. The PL011 driver was using reg_base (IPA) directly as dev->base, causing a fault when accessing UART MMIO.
Patch 1 adds arm,sbsa-uart to the compatible string list so the PL011 driver can match the virtual PL011 node inserted by Xen in the guest DTB.
Patch 2 maps the UART MMIO through the fixmap page table when running on Xen, consistent with how other devices are mapped
Related Work
Issue : #1882
PR Checklist
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